A Hybrid Anion for Ionic Liquid and Battery Electrolyte Applications: Half Triflamide, Half Carbonate

Abstract

The synthesis of a new imide type anion, methylcarbonate(trifluoromethylsulfonyl)imide (MCTFSI) is described and the physicochemical properties of its sodium and N‐butyl‐N‐methyl pyrrolidinium salts as well as structural information obtained by X‐ray diffraction studies of the sodium salt are discussed in terms of charge delocalisation, coordination chemistry and electrochemical behaviour with respect to the analogous imdides bis(trifluoromethanesulfonyl)imide (TFSI) and bis(fluorosulfonyl)imide (FSI). The insight obtained from studying the new anion informs and reemphasizes the concept of weakly coordinating anions and coordination chemistry in designing electrolyte salts.

A nitrogen-doped mesopore-dominated carbon electrode allied with anti-freezing EMIBF4–GBL electrolyte for superior low-temperature supercapacitors

“…In previous reports, researchers only focused on either the low-temperature behavior of the electrolyte or the roomtemperature performance of the electrode. For example, a cascade of pioneering attempts at establishing composite electrolytes, such as (Pip 13 FSI) 0.5 (Pyr 14 FSI) 0.5 , 11,12 TEATFB/ DOL, 13 and MeEt 3 N + /ACN/DOL, 14 have been geared towards addressing the freezing issue of ILs. However, the estimated energy densities are still unsatisfactory due to volatilization of the solvent, inferior voltage-tolerance or, especially, poor compatibility between the electrolyte and the electrode.…”

Electrolytes for Lithium (Sodium) Batteries Based on Ionic Liquids: Highlighting the Key Role Played by the Anion

“…The example of the [MCTFSI] − anion recently investigated by our group as its sodium and [C 4 mpyr] + salts provide further insight into the effect of substituting trifluoro‐ and fluorosulfonyl groups on imide‐type anions with carbonyl based functional groups. The solid–liquid phase transition behavior and short‐term thermal stability for the sodium and pyrrolidinium carbimide salts, examined by DSC and TGA respectively, show values between the corresponding [cation][TFSI] and [cation][FSI] salts.…”

“…An assessment of the coordination environment of the recently reported [MCTFSI] − anion in its Li salt cannot be made because crystallographic data are not available. A comparison of Na[MCTFSI] with its [TFSI] − equivalent shows that replacement of one tetrahedral O 2 S‐CF 3 group by a trigonal and less electron withdrawing OC−OCH 3 group leads to significant differences in the Na coordination environment (Figure ).…”

“…Despite being crucial, the development of new anions for LIB electrolyte applications has been moving at a slow pace, partly due to the demands of the requirement of suitable physicochemical properties and partly because of synthetic challenges. The latter are strikingly obvious when reviewing the fairly recent contributions to the field from Finze et al.…”

Unraveling Ion Dynamics and Interactions in an Ionic Liquid Electrolyte with a Protonated Anion for Lithium Batteries

“…In order to achieve a dendrite-free lithium battery, Chen et al 7 designed a heteroatom Si substituent based on an imidazolium TFSI IL, which showed low viscosity and high conductivity values. Gunderson-Briggs et al 26 have also reported a new IL based on a hybrid anion, methyl-carbonate(trifluoromethylsulfonyl)imide (MCTFSI). They investigated the impact of this anion component in electrolytes and ILs and demonstrated the ability of the MCTFSI anion to act as a chelating or monodentate ligand, creating three unique sodium environments in the salt form and making it better coordinating to sodium than the TFSI analogue.…”