Hydroxyl Functionalized Pyridinium Ionic Liquids: Experimental and Theoretical Study on Physicochemical and Electrochemical Properties.

Structurally modified hydroxyl functionalized pyridinium ionic liquids (ILs), liquid at room temperature, were synthesized and characterized. Alkylated N-(2-hydroxyethyl)-pyridinium ILs were prepared from alkylpyridines via corresponding bromide salts by N-alkylation (65-93%) and final anion exchange (75-96%). Pyridinium-alkylation strongly influenced the IL physicochemical and electrochemical properties. Experimental values for the ILs physicochemical properties (density, viscosity, conductivity, and thermal decomposition temperature), were in good agreement with corresponding predicted values obtained by theoretical calculations. The pyridinium ILs have electrochemical window of 3.0-5.4 V and were thermally stable up to 405°C. The IL viscosity and density were measured over a wide temperature range (25-80°C). Pyridine alkyl-substitution strongly affected the partial positive charge on the nitrogen atom of the pyridinium cations, as shown by charge distribution calculations. On-going studies on Mg complexes of the new ILs demonstrate promising properties for high current density electrodeposition of magnesium.

Rational Design of Mixed Solvent and Porous Graphene-Supported Spinel Oxide Electrodes for High-Rate and Long Cycle-Life Mg Batteries.

The development of Mg batteries based on the interfacial charge storage mechanism, where the capacity originates from capacitive processes and the solvent-related interfacial reactions, could efficiently circumvent the challenge of intercalation-based Mg batteries with sluggish kinetics. In this work, the proposed Mg organohaloaluminate mixture electrolyte is reported to improve the charge storage performance of the graphene-supported cathodes, resulting in both high cycling stability (91% capacity retention after 2000 cycles) and high rate capability (51% capacity retention when the current density increases by 100 times). The experimental and computational studies have revealed that the exceptional cell performance originates from the optimized electrode/electrolyte interface, where the highly reversible interfacial reactions occur with the 1,2-dimethoxyethane additive in the typical all-phenyl complex electrolyte. The fast charge-transfer kinetics along the surface of highly porous and conductive graphene-supported electrodes have also been observed.

Synthesis of magnesium complexes of ionic liquids with highly coordinating anions.

Magnesium(ii) complexes, [Mg2+(hfac-)3][Cation+], were prepared as solids from hydrophobic hexafluoroacetylacetonate ionic liquids ([Cation+][hfac-] ILs) and Mg(Tf2N)2. 1-Butyl-3-methylimidazolium ([C4mim]), N-butylpyridinium ([C4Pyr]), N-butyl-N-methylpiperidinium ([C4Pip]), N-hexyl-N-methylmorpholinium ([C6Morp]) and N-butyl-N-methylpyrrolidinium ([C4pyrr]) were used as cationic cores. The [C4Pip][hfac], [C4Pyr][hfac] and [C6Morp][hfac] ILs were prepared for the first time. New Mg(ii) complexes, [C4mim][Mg(hfac)3], [C4Pip][Mg(hfac)3], [C4Pyr][Mg(hfac)3], [C6Morp][Mg(hfac)3] and [C4Pyrr][Mg(hfac)3], were obtained from the [hfac] based ILs. The crystal structures of the novel Mg(ii) complexes show the coordination of three [hfac] anions to the Mg2+ ion through the two oxygen atoms of each [hfac] anion.