Acyclic and Cyclic Alkyl and Ether-Functionalised Sulfonium Ionic Liquids Based on the [TFSI]- and [FSI]- Anions as Potential Electrolytes for Electrochemical Applications

Triethylsulfonium-Based Ionic Liquids Enforce Lithium Salts Electrolytes

The demand for energy cheap production and efficient storage is huge nowadays. Sulfonium-based ionic liquids were shown to exhibit a useful set of physical-chemical and electrochemical properties which make them...

Hydrogen bond donor functionalized poly(ionic liquid)s for efficient synergistic conversion of CO2 to cyclic carbonates

The development of metal-free, high effective and recyclable catalysts plays a pivotal role in transforming CO2 into high value-added products such as cyclic carbonates. In this paper, we introduced the hydrogen bond donor (HBD) groups into poly(ionic liquid)s via free radical polymerization, which successfully combined the HBD and ionic liquids (ILs) into one heterogeneous catalyst. The HBD could synergistically activate epoxides with hydroxyl functionalized ionic liquids and efficiently catalyze the cycloaddition of CO2 into cyclic carbonates. The yield of propylene carbonate (PC) reached 94% (at 105 °C, 2 MPa CO2, 3 h), which far exceeded poly(ionic liquid)s without HBDs functionalization (PC yield 72%), and even approached bulk ionic liquids (PC yield 95%). Moreover, HBD-functionalized poly(ionic liquid)s (HPILs) exhibited excellent recyclability after five runs and afforded wide substrate scope. According to the experimental results, 1H NMR spectra and density functional theory (DFT) calculations showed 2-hydroxyethyl methacrylate (HEMA) and the hydroxyl of ILs would form strong H-bonds with epoxides contributing to the ring-opening process of epoxides, and a possible HBD and nucleophilic anion synergistically catalytic mechanism was proposed. The method herein paved a brand new way for green technology and utilization of poly(ionic liquid)s.

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

In this work, the physical, transport and electrochemical properties of various electrolytic solutions containing the 1-propyl-1-methylpyrrolidinium bis[fluorosulfonyl]imide ([C3C1pyr][FSI]) mixed with the lithium bis[(trifluoromethyl)sulfonyl]imide (Li[TFSI]) over a wide range of compositions are reported as a function of temperature at atmospheric pressure. First, the ionicity, lithium transference number, and transport properties (viscosity and conductivity) as well as the volumetric properties (density and molar volume) were determined as a function of lithium salt concentration from 293 to 343 K. Second, the self-diffusion coefficient of each ion in solution was measured by nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradients (PFG). Moreover, an analysis of the collected nuclear Overhauser effect (NOE) data along with ab initio and COSMO-RS calculations was conducted to depict intra and intermolecular neighbouring within the electrolytic mixtures. Based on this analysis, and as expected, all activation energies increase with the Li[TFSI] concentration in solution, and all activation energies were determined from the self-diffusion data for all ions. Interestingly, regardless of the composition in solution, these activation energies were similar, except for those determined for the [FSI]− anion. The activation energy of [FSI]− self-diffusion relatively decreases compared to the other ions as the lithium salt concentration increases. Furthermore, the lithium transference was strongly affected by the lithium salt concentration, reaching an optimal value and an ionicity of approximately 50 % at a molality close to 0.75 mol · kg−1. Finally, these electrolytes were used in lithium-ion batteries (i.e. Li/NMC and LTO/NMC), demonstrating a clear relationship between the electrolyte formulation, its transport parameters and battery performance.