Industrial applications of ionic liquids

Publisher Copyright: © Springer International Publishing Switzerland 2015.The various categories of cations & anions and purification of ionic liquids are reviewed. The intrinsic properties of ionic liquids make purification difficult and therefore a special emphasis is placed on currently employed purification methodologies together with ionic liquid impurities. For the same reason highlighted above characterization of ionic liquid impurities presents unique challenges; the available methods and some of the issues of their use are also reviewed. This chapter gives a survey on the pilot plants and industrial processes of ionic liquids. Moreover, challenges, issues, and recycling methods of ionic liquids in industrial developments are also discussed.Peer reviewe

Improved Electromechanical Stability of the Li Metal/Garnet Ceramic Interface by a Solvent-Free Deposited OIPC Soft Layer

Publisher Copyright: ©Ceramic electrolyte-based solid-state batteries suffer from instability at the Li metal-ceramic interface, resulting in poor and irregular lithium electrodeposition and high interfacial resistance. Here, we report the deposition, by spin coating, of an organic ionic plastic crystal (OIPC) soft layer on the surfaces of Li metal and a ceramic garnet Li7La3Zr2O12 (LLZO) electrolyte. This soft interfacial layer facilitates enhancement of Li-ion transport between Li metal and the ceramic electrolyte, increasing slightly the total conductivity of the composite OIPC-LLZO solid electrolyte (up to 1.1 × 10-3 S·cm-1) and reducing the area-specific resistance (ASR) (by up to five times, e.g., from 640 to 120 ω·cm2). Such an achievement is crucial for the integration of solid inorganic electrolytes in all-solid-state batteries as well as the development of stable and efficient devices. The deposition of the OIPC thin layer (500 nm) was carried out by solvent-free spin coating, thus preventing any potential issues resulting from metallic lithium reacting with organic solvents. At room temperature, a solid and homogeneous soft layer was deposited between the Li metal anode and the LLZO ceramic electrolyte. The interfacial resistance was studied via SEM and EIS, and the evolution of Li transport between the two materials was followed by employing Li-ion stripping-plating experiments. Finally, this interfacial soft layer was integrated in a full cell (consisting of Li/OIPC/LLZO/OIPC/LFP) and demonstrated improved galvanostatic cycling performances due to the lower ASR.This research was carried out at CIC Energigune (Spain) and at Tecnalia Research and Innovation, funded by Gobierno Vasco, within the project framework ELKARTEK CICe 2018, and EU-horizon 2020 project IMAGE, under the grant agreement No 769929. A.L. also thanks IKERBASQUE for financial support. The authors thank Dr. Nicholas Drewett for his kind advice for polishing the English version.Peer reviewe

Extraction of silver(i) from aqueous solutions in the absence and presence of copper(ii) with a methimazole-based ionic liquid

The ionic liquid (IL) 2-butylthiolonium bis(trifluoromethanesulfonyl)amide, [mimSBu][NTf2], facilitates the efficient extraction of silver(i) from aqueous media via interaction with both the cation and anion components of the IL. Studies with a conventional aqueous-IL two phase system as well as microextraction of silver(i) by a thick IL film adhered to an electrode monitored in situ by cyclic voltammetry, established that [mimSBu][NTf2] can extract electroactive silver(i) ions from an aqueous solution. The pH of the aqueous phase decreases upon addition of [mimSBu]+, which is attributed to partial release of the hydrogen attached to the N(3) nitrogen atom of the imidazolium ring. The presence of silver(i) further increase the acidity of the aqueous phase as a consequence of coordination with the IL cation component. Voltammetric and 1H and 13C NMR techniques have been used to establish the nature of the silver(i) complexes extracted, and show that the form of interaction with the IL differs from that outlined previously for the extraction of copper(ii). Insights on the competition established when silver(i) is extracted in the presence of copper(ii) are provided. Finally, it is noted that metallic silver can be directly electrodeposited at the electrode surface after extraction of silver(i) into [mimSBu][NTf2] and that back extraction of silver(i) into aqueous media is achieved by addition of an acidic aqueous solution.<br /

Physical and electrochemical properties of thioether-functionalized ionic liquids

The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 &deg;C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry. Potential windows of the ionic liquids have been obtained at glassy carbon, platinum, and gold electrodes and found to be the largest at glassy carbon, but are limited by oxidation of the thioether-functionalized cation. The voltammetry of IUPAC reference potential scale systems, ferrocene/ferrocenium, cobaltocenium/cobaltocene, and decamethylferrocene/decamethylferrocenium have been evaluated, with the last being most widely applicable. Nonadditivity of Faradaic current is found in the voltammograms of decamethylferrocene in the presence of ferrocene and cobaltocenium. Diffusion coefficient, viscosity, ionic conductivity, double layer capacitance, and other physical properties have also been measured. The dependence of the diffusion coefficient vs viscosity follows the Stokes&minus;Einstein relationship. The properties of the ionic liquids are compared with the related imidazolium family of ionic liquids.<br /

Nitrile functionalized methimazole-based ionic liquids

The alkylation reaction of 2-mercapto-1-methylimidazole 1b with 2-chloroacetonitrile and 2-chloropropionitrile produced S-alkyl methimazole chlorides 2a and 2b which were subjected to anion metathesis with lithium bis(trifluoromethanesulfonyl)amide, LiNTf2, to afford nitrile functionalized methimazole-based room temperature ionic liquids 3a and 3b in 94% and 89% yields, respectively. Ionic liquids 3a and 3b have reasonably wide electrochemical windows. The efficient extraction of Ag+ from aqueous media into 3a and 3b is also reported.<br /