High Viscosity Of Ionic Liquids Research Articles

The Coiling Effect in Ether Ionic Liquids: Exploiting Acetate as a Probe for Transport Properties and Microenvironment Analysis.

The inherently high viscosity of ionic liquids (ILs) can limit their potential applications. One approach to address this drawback is to modify the cation side chain with ether groups. Herein, we assessed the structure-property relationship by focusing on acetate (OAc), a strongly coordinating anion, with 1,3-dialkylimidazolium cations with different side chains, including alkyl, ether, and hydroxyl functionalized, as well as their combinations. We evaluated their viscosity, thermal stabilities, and microstructure using Raman and infrared (IR) spectroscopies, allied to density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. The viscosity data showed that the ether insertion significantly enhances the fluidity of the ILs, consistent with the coiling effect of the cation chain. Through a combined experimental and theoretical approach, we analyzed how the OAc anion interacts with ether ILs, revealing a characteristic bidentate coordination, particularly in hydroxyl functionalized ILs due to specific hydrogen bonding with the OH group. IR spectroscopy showed subtle shifts in the acidic hydrogens of imidazolium ring C(2)-H and C(4,5)-H, suggesting weaker interactions between OAc and the imidazolium ring in ether-functionalized ILs. Additionally, spatial distribution functions (SDF) and dihedral angle distribution obtained via AIMD confirmed the intramolecular hydrogen bonding due to the coiling effect of the ether side chain.

(Best Poster Award - 2nd Place) Energy Harvesting from CO2 Emission Exploiting an Ionic-Liquid Based Electrochemical Capacitor

Global warming is one of the most serious problems that the humanity is facing in his history.Since 1900 to nowadays, the global temperature has risen by 1 °C and, according to the scientificcommunity, the cause is related to the climate-changing emissions due to anthropogenic activities.In order to avoid an environmental disaster, 196 countries have signed the Paris agreement thataims to maintain global warming below 1.5 °C compared with pre-industrial levels.The reduction of greenhouse gas emissions is a key issue in contemporary science, and in thiscontext, the ability of certain ionic liquids (ILs) to capture carbon dioxide has attracted a lot ofinterest. The idea presented in this work is to design an electric double layer supercapacitor whichis able to harvest energy by exploiting the reaction between an ionic liquid and carbon dioxide. Inparticular, the system consists of two carbon-based electrodes and a polymeric separator soakedin ionic liquid. The use of carbon electrodes ensures a high surface area and excellent electricalconductivity while imidazole-based ionic liquid acts and as electrolyte and as capture media.The operating principle of this system is a novel mechanism which exploits the formation of avoltage drop across the device when the electrode-IL interfaces are different; the two differentinterfaces are ensured by the presence of imidazole carbamate in a part of the cell (Im − CO2reaction’s product) and just imidazole in the other part.Unfortunately the high viscosity of ionic liquids affects a lot the carrier transport and consequentlythe device’s performance too; this aspect worsens when imidazole reacts with CO2. Improved ionmobility is achieved by reducing the ion pairing through the use of high dielectric solvents capableto screen the ions’ electric field. Polar aprotic solvents tend to have large dipoles making themsuitable for the solvation of charged species.Several mixtures have been analyzed to detect the best dilution which guarantees high ionic mobilitystill maintaining a large amount of active species.A further performance improvement has been achieved through the engineering of the electrodes,namely the capacitance of the supercapacitor has been enhanced by exploiting the huge specificsurface area of the activated carbon.The results show that all the upgrades mentioned lead to an improvement of 500 times in terms ofharvested energy.Acknowledgement: This result is part of a project that has received funding from the European Research Council(ERC) under the European Union’s ERC Starting Grant Grant agreement No. 949916 Figure 1

Molecular Understanding of Charging Dynamics in Supercapacitors with Porous Electrodes and Ionic Liquids.

Porous electrodes and ionic liquids could significantly enhance the energy storage of supercapacitors. However, they may reduce the charging dynamics and power density due to the nanoconfinement of porous electrodes and the high viscosity of ionic liquids. A comprehensive understanding of the charging mechanism in porous supercapacitors with ionic liquids provides a crucial theoretical foundation for their design optimization. Here, we review the progress of molecular simulations of the charging dynamics in supercapacitors consisting of porous electrodes and ionic liquids. We highlight and delve into the breakthroughs in the ion transport and charging mechanism for electrodes with subnanometer pores and realistic porous structures. We also discuss future directions for the charging dynamics of supercapacitors.

A proposed method of bubble absorption-based deep dehumidification using the ionic liquid for low-humidity industrial environments with experimental performance

Liquid desiccant deep dehumidification (LDDD) is an excellent way to achieve low-carbon transformation of low-humidity industrial buildings. Currently, it is essential to improve its ability to produce lower humidity air (i.e., with a dew point below −10 °C). Functional ionic liquids (ILs) with extremely low vapor pressure, non-crystallization, and non-corrosion are ideal substitutes for high mass fraction aqueous inorganic solutions (e.g., LiCl, LiBr) in traditional liquid desiccant deep dehumidification. Meanwhile, the bubble absorption mode allows water vapor to condense on the huge contact surface between the bubbles and desiccant. Accordingly, it is expected to solve the low wettability and transfer unit number (NTUm) in falling-film absorption mode caused by the high viscosity of ILs. Thus, a new method of bubble absorption-based deep dehumidification using the IL is proposed. To validate it, the bubble absorption-based deep dehumidifier using a novel ionic liquid (BADD-IL) is developed and tested under different operating conditions. Besides, its moisture effectiveness is compared with those of falling film absorption-based dehumidifiers. The results show that increasing the liquid height, superficial velocity, as well as lowering the solution temperature, can strengthen the deep dehumidification performance, effectiveness and cooling ability to varying degrees. The increase of liquid height and superficial velocity promotes the gas-liquid interfacial area from different aspects, thus enhancing the transfer efficiency. Notably, the insufficient interfacial areas caused by low solution temperature cannot prevent better transfer efficiency dominated by high potential difference. Moreover, the NTUm of BADD-IL has a wide adjustment range (0.1–1.7), and the minimum supply air humidity ratio and maximum moisture effectiveness can reach 1.1 g/kgda and 81%, respectively. In overall, this study aims to further explore the deep dehumidification potential of ILs, and inform ideas for the LDDD development.

Lysine‐Based Ionic Liquid Enables Peptides to Reverse Skin Photoaging: From Leaves to Roots

AbstractPeptides and proteins are pharmacologically active and highly safe; however, their local delivery remains a challenge in the field of drug delivery. Based on this, a novel lysine‐based ionic liquid via proton transfer between lysine and malic acid that can overcome the difficulties in the application of copper peptides is developed. Density functional theory, molecular docking simulations, and experimental validation demonstrate the chemical stability of this ionic liquid. Furthermore, by combining it with a vegetable oil system, a biocompatible lysine‐based ionic liquid microemulsion system is constructed, which perfectly combines the high viscosity of ionic liquids and low viscosity of microemulsions. Multi‐dimensional analysis shows that the system not only leads to a dramatic elevation in the local penetration of copper peptides, but also enables copper peptides to effectively suppress skin aging. In addition, transcriptome sequencing analysis reveals that the system primarily regulates p53, p16, and ECM‐related signaling pathways to combat photoaging in the skin. Overall, a noninvasive, efficient, and convenient anti‐aging system with enormous potential is developed for the clinical prevention and treatment of skin photoaging.

SO2 Adsorption and Kinetics Analysis during Supported Triethanolamine Acetate Ionic Liquid Desulfurization.

Ionic liquid desulfurization is an effective method for achieving green and circulating desulfurization. To overcome the negative impact of the high viscosity of ionic liquids on the desulfurization process, an economical and efficient supported ionic liquid-triethanolamine acetate ionic liquid/silica (TAIL/SiO2) was prepared in this study. TAIL is synthesized using triethanolamine and acetic acid and subsequently loaded onto silica gel particles. The effects of the reaction temperature, humidity, silica particle size, and loading ratio on SO2 adsorption are investigated using a fixed-bed reactor. The results indicate that the surface of the silica gel loaded with ionic liquid formed uneven spherical clusters, and the aggregate volume increased with an increase in the loading ratio. The TAIL/SiO2 sulfur capacity could be effectively increased by increasing the loading ratio (exceeding 0.74 is unfavorable), decreasing the silica particle size, and reducing the reaction temperature and moisture content. The maximum sulfur capacity can reach 124.98 mg SO2/(g TAIL/SiO2) under experimental conditions, which is higher than that of activated carbon. The Bangham rate model effectively predicts the kinetics of the adsorption process of SO2.

Effect of dilution on the performance of ionic liquids in milliflow solvent extraction applications: Towards integration of extraction, scrubbing and stripping operations with in-line membrane-based phase separation

The combination of ionic liquids (ILs) and millifluidic reactors is often suggested as a form of process intensification. The high viscosity of ILs has, however, raised concerns about hydrodynamics, mass-transfer enhancement and the ability to integrate several millifluidic operations. In the present study the performance of a quaternary ammonium hydrogensulfate IL, [A336][HSO4], in a millifluidic solvent extraction (SX) process was evaluated and compared with various, lower viscosity solutions of the IL in a diluent. Dilution of [A336][HSO4] significantly improved the slug flow hydrodynamics by reducing the film thickness, avoiding the loss of secondary recirculations inside the plugs and improving stability at elevated flow rates. The overall mass-transfer performance of the system was also improved upon dilution by a balancing of mass-transfer and reaction limitations. It was also observed that dilution reduced reagent consumption and improved the extraction selectivity. In addition, the decrease of the viscosity of the IL upon dilution facilitated the use of an in-line membrane-based phase separator. An integrated millifluidic set-up containing an extraction, scrubbing and stripping reactor was built using these in-line phase separators and applied to the SX purification of germanium from a synthetic zinc refinery residue leachate. The integrated reactor system was operated using a 30 vol% [A336][HSO4] dilution in p-cymene and successfully run for 4 h without any loss in separation performance or stability.

Low viscous aminoalkyl‐phenyl‐silane with π–π interaction and its optimal SO2 capture condition

AbstractThe high viscosity of ionic liquids (ILs) limits their practical application in SO2 capture. In this work, the low viscous aminoalkyl‐phenyl‐silanes were synthesized to capture SO2. The π–π interaction between phenyl groups reduced the volatility of aminoalkyl‐phenyl‐silanes greatly, but it did not increase their viscosity significantly. Among them, N‐[(dimethylphenylsilyl)methyl]‐N‐methylbenzenemethanamine (DPSA) containing two phenyl groups exhibited the strongest π–π interaction. Therefore, the thermal decomposition temperature reached 150°C, while its viscosity was only 8.45 mPa·s at 25°C, which is much lower than that of ILs. The absorption enthalpy and entropy change of DPSA absorption reaction were −79.284 kJ/mol and −224 J/mol/K, respectively. These values are more negative than those of SO2 capture reaction with ILs. An objective function was proposed to obtain the optimal absorption and desorption temperature. Furthermore, five cycles of regeneration experiments indicated that DPSA possessed good regeneration ability.

Recent Advances in Supported Ionic Liquid Membrane Technology in Gas/Organic Compounds Separations

Abstract: The development of the convenient separation processes is a major challenge being examined by scientists and technologists due to its industrial applications. The supported liquid membrane (SLM) technology has been widely employed to separate several species, like permeable gas from binary gaseous mixtures, metal ions, and organic and biological compounds. The main reason for the limited use of SLMs in the industry is their short life and less stability due to the high volatility of traditional organic solvents. Room-temperature ionic liquids (RTILs) are environmentally benign designer salts, exhibit negligible volatility, show good thermal stability, and have remarkable solubility, thus, acting as an alternative solvent to overcome the drawbacks of SLMs. Besides, the high viscosity of ionic liquids (ILs) offers good capillary force, which prevents their flow into membrane pores even under high pressure. Moreover, their tuned properties make them amenable compounds for their immobilization into membrane pores to provide supported ionic liquid membranes (SILMs) with good mechanical strength. In literature (from 2007 to the present), a variety of SILMs have been designed, synthesized, and employed in the field of separation science. This review is mainly focused on the applications of SILMs in the separation of more permeable gases (CO2, O2, CO, H2, and C2H4) from binary gas mixtures as well as the separation of organic compounds (organic acids, alcohols, aromatic hydrocarbons, amines, reactants and products of transesterification reaction, nitrogen- and sulfur-containing aromatic compounds) from distinct mixtures.

Molecular Simulation and Experimental Study on Low-Viscosity Ionic Liquids for High-Efficient Capturing of CO2

In recent decades, ionic liquids (ILs) have been developed as an ideal and reversible decarbonization solvent. However, some pitfalls, such as the low CO2 capacity and high viscosity of ILs, limit their further scale up and industrial application. Therefore, in this work, three novel functional ILs [N8881][NIA], [N8881][For], and [N8881][Ac] were synthesized after using a molecular design method to capture CO2 at 303.15–333.15 K and pressures up to 1000 kPa. The experimental results illustrate that [N8881][NIA] presents the smallest viscosity and the highest CO2 solubility. The capacity order is [N8881][NIA] > [N8881][For] > [N8881][Ac] under the same experimental conditions. The CO2 recyclability experiments using [N8881][NIA] show the stability of CO2 solubility after 5 cycles. The quantum chemistry simulations at the level of DFT/B3LYP with 6-311++G(d,p) basis sets were used to study the CO2 absorption mechanism in the studied ILs from the molecular viewpoint. Simulation results illustrated that the higher interaction energy between CO2 and ILs means more CO2 absorbed in these ILs, which agreed well with the experimental results. The atoms in molecules theory and the function of the reduced density gradient were also used to calculate the interactions in these IL–CO2 systems. Results show that the majority of these interactions present an electrostatic character.

Pressing matter: why are ionic liquids so viscous?

Room temperature ionic liquids are considered to have huge potential for practical applications such as batteries. However, their high viscosity presents a significant challenge to their use changing from niche to ubiquitous. The modelling and prediction of viscosity in ionic liquids is the subject of an ongoing debate involving two competing hypotheses: molecular and local mechanisms versus collective and long-range mechanisms. To distinguish between these two theories, we compared an ionic liquid with its uncharged, isoelectronic, isostructural molecular mimic. We measured the viscosity of the molecular mimic at high pressure to emulate the high densities in ionic liquids, which result from the Coulomb interactions in the latter. We were thus able to reveal that the relative contributions of coulombic compaction and the charge network interactions are of similar magnitude. We therefore suggest that the optimisation of the viscosity in room temperature ionic liquids must follow a dual approach.

Ionic Liquid Impedance Sensor for Continuous Low Temperature CO2 monitoring

There is a significant need to develop sensor technology for applications in extreme environmental conditions. Robust gas sensors that can continuously monitor specific gaseous analytes in harsh environments are essential for a variety of applications such as environmental monitoring and greenhouse gas emissions in Arctic where temperatures are constantly in the sub-zero range. For efficient operation and long-term stability, these devices require sensing materials that can function at subzero temperatures as well as non-invasive readout mechanisms. Electrochemical techniques are advantageous for continuous gas sensing due to their cost effectiveness, simplicity, portability and easy miniaturization of the instrumentation. However, the application of constant or varying DC potential in commonly used voltametric and amperometric detection methods may result in interfacial redox reactions and formation of new products that could poison the sensor materials and take part in unfavorable side reactions. Electrochemical impedance spectroscopy (EIS) is a non-invasive alternate technique which measures impedance changes originating from change in polarization of the electrode-electrolyte interface upon addition of analyte gases. Compared to traditional aqueous electrolytes, the unique solvent and electrolyte properties of ionic liquids (ILs) enable them to operate in extreme environments without undergoing physical or chemical changes. In this presentation, we will discuss our results for the development of an ionic liquid (IL) based miniaturized impedance sensor for continuous CO2 monitoring in the -15 to 40oC temperature range using a microfabricated electrochemical sensor designed and fabricated with Pt black electrodes and hydrophobic [Bmpy][NTf2] ionic liquid electrolyte. The large hydrophobic NTf2 anion is shown to weaken cation−anion interactions, enabling a higher absorptivity of CO2. It also weakens water−anion interactions and thus impedes the absorption of H2O, minimizing the interference from humidity at the ambient conditions. Pt black provides a high surface area that allows simple and robust fabrication of planar electrodes on flexible polymer membranes. A non-invasive single frequency impedance spectroscopy (SF-EIS) method was demonstrated for the continuous and quantitative detection of CO2. In this method, impedance changes arising from increasing amounts of added CO2 analyte and [Bmpy][NTf2] IL at open circuit potential were measured at a set frequency of 1 Hz at different temperatures. It was seen that the impedance increased with decreasing temperature, and decreased with increasing amounts of added CO2. A linear relationship between the CO2 gas concentration and impedance was obtained, and increased sensitivity for CO2 detection was observed at low temperatures with a maximum slope of -5.092 ohm/%CO2 seen at -15oC. The same miniaturized and flexible planar electrochemical sensor with [Bmpy][NTf2] IL electrolyte was tested repeatedly for continuous sensing of CO2 at subzero temperatures over a two and a half month period, during which good stability and repeatability were obtained. To explain our impedance trend, we hypothesize that the high viscosity of IL at low temperature will result in the formation of a more packed, concentrated layer of ionic charges on the electrode surface. In the presence of CO2, the relatively rigid IL-electrode double layer at low temperature can be beneficial for chemical sensing since the molecular interactions between the CO2 analyte and [Bmpy][NTf2] could result in decreasing resistance and increasing conductivity by decreasing ionic attractions in the IL. Consequently, the high viscosity of ILs at low temperature, which is usually considered a limitation to practical in amperometric sensing, converts to an advantage in impedance sensing since ordered and concentrated electric double layer could provide high sensitivity and selectivity. In addition, the increased initial impedance at low temperature due to high IL viscosity and density is beneficial for our signal-off sensing mechanism. This reported CO2 sensor is among the first impedance based gas sensors shown to function continuously at sub-zero temperatures, providing CO2 measurements with good sensitivity at low cost and low power. These results obtained from our sensor show promise for potential use in real-time monitoring of carbon dioxide emissions in harsh low temperature environments, uniting the benefits of minimally invasive impedance transduction methods and robust IL sensing materials. Figure 1

Ionic Liquids As Tunable Electrolytes for Protonic Systems

INTRODUCTION The unique properties of ionic liquids (ILs) i.e. high thermal and chemical stability, non-flammability, low vapor pressure, and wider electrochemical window compared to traditional solvents, as well as the prospect that they can be tailored or custom designed for specific requirements make them all the more interesting. In recent years, ILs with organic cations have been suggested for electrolyte applications. Ionic liquids seems to be promising electrolytes in protonic systems as they exhibit good proton conducting properties.The motivation for the presented research was dictated by the growing interest in the field of the use of ionic liquids as electrolytes in metal-hydride batteries (Ni-MH) and other proton batteries (eg. based on the Si anode). The electrolytes based on ionic liquids can reduce the problem of the anode material (eg. AB5 alloy) corrosion in aqueous basic solutions, which may result in the improvement of the operation parameters of the proton batteries.The focus of this study was to check the applicability of ILs as non-aqueous electrolytes through the investigation of hydrogen sorption in Pd limited volume electrode (Pd-LVE) and AB5-LVE. Since protic ILs and their mixtures with other solvents have been recently proposed as electrolytes in metal-hydride batteries, Pd-LVE is a very good model system to carry out the preliminary study of hydrogen electrosorption in ionic liquids in view of the further research with the use of multicomponent alloys. EXPERIMENTAL The electrochemical experiments were conducted in selected, commercially available protic and aprotic ionic liquids (i.a. diethylmethylammonium triflate (DEMA-TFO), ethylammonium nitrate (EAN), 1-ethyl-3-methylimidazolium methanesulfonate (EMIm-MS) under inert gas (Ar) using three-electrode system. Pd-LVE (ca. 0.5 μm thick) or AB5-LVE (ca. 50 μm thick) was a working electrode, Ag wire was a quasi-reference electrode, and Pt or Au spiral was an auxiliary electrode. Pd-LVE were obtained electrochemically from the PdCl2 aqueous solution. AB5 alloy (LaMMNi4.1Al0.3Mn0.4Co0.45) was obtained from VARTA Microbatteries GmbH. To aprotic ionic liquid (EMIm-MS) organic acid of the same anion as in the IL (methanesulfonic acid, HMS) was added as a source of hydrogen and to increase the ionic conductivity of the obtained electrolyte. Cyclic voltammetry (CV), chronoamperometry (CA) and chronopotentiometry (CP) techniques were used to perform the electrochemical measurements. The electrodes were subjected to a hydrogen pretreatment procedure (HPP) and standard hydrogen cyclic voltammetry electrosorption experiment to obtain hydrogen absorption isotherms. RESULTS AND DISCUSSION It was observed, that the reversibility of the hydrogen sorption in Pd is significantly lower in ILs than in aqueous solutions, which may be caused by hindered proton transport due to few reasons. The first one is the high viscosity of IL, the second one is the difference of proton source, and finally the possible interactions of IL ions with the Pd electrode. Multiple hydrogen sorption in ILs (HPP) increases the reversibility of the investigated process. Preliminary HPP performed in aqueous solution of sulfuric acid facilitates further hydrogen sorption only in some cases (i.a. in EAN). Thus, it was found that the rate of hydrogen absorption is controlled rather by surface than the bulk processes. The maximum hydrogen sorption capacity (H/Mmax) obtained for Pd in protic IL (i.e. DEMA-TFO) and aprotic IL with addition of organic acid (EMIm-MS + 0.5 M HMS) is comparable with those obtained in aqueous solutions of acids and bases, reaching the value of ca 0.7. Our preliminary studies of hydrogen sorption in the AB5 alloy in a mixture of an aprotic IL with the organic acid (EMIm-MS + 1 M HMS) revealed that, as in case of Pd-LVE, the electrochemical reversibility of this process is much lower in comparison with the electrosorption measurements performed in concentrated base (Fig.1), which is due to the significant difference in ion conductivity and dynamic viscosity of the tested electrolytes. Fig. 1. Cyclic voltammetry behavior of AB5 electrode in EMIm-MS + 1 M HMS, inset: cyclic voltammetry of AB5 electrode in 6 M KOH; first cycles; 2 mVs-1. CONCLUSIONS Examined protic and aprotic ionic liquids can be effectively used as electrolytes in the hydrogen sorption process as we demonstrated by the exemplary Pd-LVE electrode. The max. H/Pd ratios obtained for DEMA-TFO and nitrate protic ILs are similar (0.6-0.7) and comparable with those measured in aqueous solutions of acids and bases. Hydrogen electrosorption from aprotic ionic liquids (eg. in EMIM-MS) with different concentration of acid gives ability to tune the maximum hydrogen capacity. The max. H/Pd ratios obtained for EMIm-MS (acid concentration ca. 0.5 M) equals to ca. 0.74 (this is the same value that was obtained for this type of electrode from acidic aqueous media). Figure 1

Development of a novel functionality for a highly efficient imidazole-based ionic liquid non-aqueous solvent system for the complete extraction of target alkaloids from Phellodendron amurense Rupr. under ultrasound-assisted conditions

Solvent application in industrial processes is inevitable due to its required role in dissolving solutes, promoting mass and heat transfer, and facilitating separation and purification processes. Notably, woody plants have a high degree of fibrosis and lignification with a mass transfer barrier effect from their multi-scale structure and complex component effects, which makes it difficult for solvents to seep into these plant cells. An ultrasound-assisted complete extraction in ionic liquid non-aqueous solvent system (UACE-ILNAS) method was successfully designed and applied to achieve excellent extraction of five alkaloid components (berberine, palmatine, jatrorrhizine, magnoflorine and phellodendrine) from the bark and leaves of Phellodendron amurense Rupr. From single-factor design and response surface methodology (RSM), the significant factors affecting the average yield of the alkaloids, the ionic liquid concentration, liquid-solid ratio and ultrasonic irradiation temperature, were optimized. Under the optimal conditions, the average yields of the alkaloids from the bark and leaves of P. amurense were 4.22 ± 0.20 and 2.47 ± 0.12 mg/g, respectively, which were highly consistent with the response surface optimization and kinetics analysis results. The non-aqueous aprotic solvent dimethyl sulfoxide (DMSO) was innovatively used as a co-solvent for the ionic liquid [C4mim][OAc]. The DMSO plays a positive role in promoting penetration, helping cell wall dissolve, reducing viscosity, etc. The proposed method overcomes the poor water solubility of isoquinoline alkaloids and the negative effects from the high viscosity of ionic liquids to effectively guarantee the alkaloid quality and yield. In addition, ultrasound plays a reinforcing role in achieving full extraction. Therefore, the developed method shows good application prospects for the separation of low-polarity constituents, especially those present in woody plants.

A novel strategy to reduce the viscosity of cellulose-ionic liquid solution assisted by transition metal ions

The high viscosity of ionic liquids, even at relatively high temperatures, can greatly affect the production of cellulose fibers through the wet-spinning process. The high viscosity mainly by due to the hydrogen bond interaction between the cations and anions of ionic liquids. It is possible to reduce the viscosity by modulating the hydrogen bond interaction. In the present work, copper chloride (CuCl2) was dissolved in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl)-cellulose solution, followed by the formation of a complex with the chloride anions by converting it to [CuCl4]2− anion. Through this strategy, the extrusion velocity of the solution improved, and the produced fibers obtained smoother surfaces and shrunken diameters.

Effects of the Water Content on the Transport Properties of Ionic Liquids

Ionic liquids (ILs) have been applied in many fields in recent years, but the high viscosity of ILs has become an important factor hindering the further implementation of ILs. ILs/water binary mixtures often show a lower viscosity than pure ILs. However, the general effects of the water content on the viscosity remain unclear. In this work, the viscosities and self-diffusivity of a series of [Cnmim][Ac] (1-alkyl-3-methyl imidazole acetate) ILs were computed by molecular dynamics simulations with a water mass percentage of 0.02–10%. The results show a general rule that the viscosities of all [Cnmim][Ac] ILs (n = 1–6) first increase and then decrease by adding a certain amount of water, which correlate well with the corresponding reciprocals of self-diffusion coefficients. Interestingly, the inflection points of the viscosity gradually move forward in the direction of a lower water content when increasing the chain length, which is the result of increased hydrophobicity. Structural analysis shows that the chainlike structure of anion···water···anion is the key reason for the increase-to-decrease behavior of viscosity when water is added. Moreover, the sharp peaks of radial distribution functions between water and Ac– go up first and then move down, and the peak positions follow the same trend of inflection points.

Mixtures of Ionic Liquid and Organic Electrolyte with Improved Safety and Electrochemical Performance with Nanostructured Silicon-Anode for Li-Ion Batteries

The present rechargeable lithium-ion battery systems commonly use small amount of electrolytes based on suitable lithium salts (generally LiPF6) and organic solvents (generally alkylcarbonates, such as EC, DMC), which represent a major concern for device safety due to the flammable and volatile nature of these organic liquids. The use of these organic carbonates electrolytes allows the realization of high-performance batteries, but due to its flammability, their use also poses serious safety risks and strongly reduces the battery operative temperature range. Therefore, alternative electrolytes have been proposed and tested in the last decade [1]. Ionic liquids doped with a lithium salt are alternative electrolytes for lithium-ion batteries that offer some advantages compared to organic carbonates based liquid electrolytes. Ionic liquids display a low vapor pressure which leads to nonflammability. The main drawback of ionic liquid-based electrolytes is the low lithium-ion conductivity due to relatively high viscosity of ionic liquids. A lot of research has been devoted to developing ionic liquids with low viscosity. However, so far, these ionic liquids could be obtained only at the expense of lower thermal and/or electrochemical stability. In recent years, mixtures of organic carbonates-based electrolytes and ionic liquids have been proposed as a solution to overcome the lithium-ion transport limitations of ionic liquid-based electrolytes while improving safety due to a lower flammability than that of organic carbonates electrolytes [1, 2]. Herein, we report the results of physical-chemical and electrochemical investigations performed on mixed electrolytes based on an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI), and organic electrolytes (LiTFSI in EC/DMC) with nanostructured silicon-anode for lithium-ion batteries. The ionic conductivity, lithium-ion transference number, viscosity and electrochemical stability windows of all different ionic liquid content mixtures were investigated and compared with carbonates-based electrolyte. The specific capacity and cycling stability of the nanostructured silicon-anode were investigated at different C-rates at room temperature. A reversible capacity of 3480 mAh g-1 (of Si) at C/10 and 1600 mAh g-1 at 5C is obtained with cells having electrolyte mixture with a composition of 1:1. This study indicates that safety and electrochemical performance of the Si-anode for Li-ion battery can be improved by using mixed ionic liquid and carbonates-based electrolytes. [1] A. Guerfi, M. Dontigny, P. Charest, M. Petitclerc, M. Lagacé, A. Vijh, K. Zaghib, J. Power Sources 195 (2010) 845-852. [2] R.-S. Kühnel and A. Balducci, J. Phys. Chem. C 118 (2014) 5742-5748.

Suzuki-Miyura cross-coupling reaction in droplet-based microreactor

An ionic liquid (IL)-based Suzuki-Miyaura cross-coupling reaction was implemented successfully in a droplet-based microreactor. FC-40 fluorocarbon-based liquid was introduced as the continuous phase to disperse reactants into uniform droplets. The negligible effect of the existence of FC-40 on reaction and product analysis was clarified, and then the reaction performance within droplets was investigated under different operating conditions. The application of droplet-based microreactor not only solved the clogging problem in a microchannel due to high viscosity of ionic liquids, but also improved the reaction yield by intensifying mixing. Compared with a batch reactor, the yield in the droplet-based microreactor improved evidently, i.e., from 59.4% to 68.7% at 83 °C with the reaction time at 10 min.

An Ionic Liquid/Poly(vinylidene fluoride‐co‐hexafluoropropylene) Gel‐Polymer Electrolyte with a Compatible Interface for Sodium‐Based Batteries

AbstractIonic liquid gel‐polymer electrolytes (GPEs) have attracted increasing attention, owing to their merits of safety and reliability. However, the high viscosity of ionic liquid requires better transmission channels for the polymer. Exploration of ionic liquid GPEs with high ionic conductivity and excellent transmission channels is a possible strategy to optimize the practicability of sodium‐based technology. A flexible GPE with high ionic conductivity and excellent transmission channels is synthesized with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF−HFP) as the base material blended with the water‐insoluble ionic liquid N‐methyl‐N‐butyl piperidine difluoromethylimide ([PP14][TFSI]) by using a phase‐inversion technique. A polydopamine coating is then introduced into the GPE to improve wettability and compatibility. The thermal decomposition temperature of the prepared gel‐polymer films is greater than 450 °C. Our activated GPE achieves good safety, a wide electrochemical window, and high ionic conductivity. When testing a sodium‐ion battery with Prussian blue as the cathode, the batteries show good cycling performance. Our results suggest that the as‐prepared GPE can be efficiently and safely used in sodium‐ion batteries.

Influence of Microstructure and Interaction on Viscosity of Ionic Liquids

The high viscosity of ionic liquids (ILs) is one of the impediments to their application in industry. Understanding the relationship between structure and viscosity is a key issue for the directed design of ILs with low viscosity. In this work, the microstructures and interactions of three representative imidazolium-based ILs were studied by quantum chemistry calculations and molecular dynamics simulations to investigate the origin of different viscosities. An all-atom force field for difluorophosphate ([PO2F2]) anion was developed. The sandwich structures of hydrogen-bond networks were observed. A relationship between the number and energy of hydrogen bonds and the viscosity was proposed. The order of interaction energies is consistent with the trend of experimental viscosities. The simulation studies suggest that the hydrogen bonds and interaction energy play important roles in determining the viscosity of an IL.