Glycol Dimethyl Ether Research Articles

Preparation and Characterization of Thermoresponsive PEG-Based Injectable Hydrogels and Their Application for 3D Cell Culture.

We report here the synthesis of a series of ethylene glycol-based triblock copolymers containing a hydrophilic middle segment of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and two temperature-responsive segments of diethylene glycol methyl ether methacrylate (DEGMA) at both ends via the reversible addition-fragmentation chain-transfer (RAFT) polymerization. While the corresponding temperature-responsive homopolymer (PDEGMA) and the diblock copolymer (PDEGMA-b-PPEGMA) could not form a gel, the triblock copolymers (PDEGMA-b-PPEGMA-b-PDEGMA) could form a physical gel at certain concentrations and at temperatures above the lower critical solution temperature (LCST). This sol-gel transition is fully reversible and can be repeated several times. Depending on the chain length of the middle block and two end blocks, a physical gel could be formed at a minimum polymer concentration of 5 wt %. In addition, a mechanically strong gel could be easily formed within 5 s at the maximum concentration of 20 wt % and at a temperature of 37 °C. Considering the good cell compatibility and soft rubbery nature of the triblock copolymers, they can potentially be used as injectable scaffold for cell culture and tissue engineering applications.

Enhanced Cycling Performance of Li–O2 Battery by Highly Concentration Electrolyte of LiFSA/Methyl Pivalate

Finding a stable organic electrolyte to improve the cycling life of lithium-oxygen (Li–O2) batteries is of primary importance. Tetra(ethylene) glycol dimethyl ether (TEGDME) based electrolytes are the most commonly used in Li–O2 batteries, however, they are still unstable in the presence of superoxides or singlet oxygen, and finally result in the performance reduction during long-term operation. Here a stable electrolyte designed to solve this issue is reported. By mixing dissociative LiFSA salt with methyl pivalate (MP) solvent at super-high concentration, an unusual three-dimensional network of FSA− anions and solvent molecules strongly complexed with Li+ ions is obtained. This unusual structure of the superconcentrated solution is different from the dilute and moderately concentrated solutions. Due to its special structural characteristics, the Li–O2 battery with the superconcentrated LiFSA/MP electrolyte exhibited excellent cycling stability, which was about 4 times higher than the battery with the conventional TEGDME based electrolyte.

Molecular Structure and Electron Affinity of Metal-Solvent Complexes: Insights from Density Functional Theory Simulations

A molecular level understanding of the structure and energetics of the monovalent and divalent metal ion complexes is of great importance for development of next-generation batteries. In this contribution, Density Functional Theory (DFT) simulations at the ωb97xD/6–31 + G(d,p) level of theory are performed to investigate the interaction of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Zn2+) with 26 organic solvent molecules. The reduction energetics (electron affinity and reduction potential) and structural responses of the solvent molecules and the molecular complexes are discussed. The DFT calculations are carried out to investigate the structure, energetics and electron affinities of chelated complexes of water (H2O), tetrahydrofuran (THF) and di-methoxy ethane (DME) solvent molecules. Additionally, ab initio dynamic simulations (AIMD) at 298 K using atom centered density matrix propagation (ADMP) formalism are performed to understand the spontaneous structure formation upon electron attachment of the metal ion-solvent complexes. The ADMP simulations indicate the decomposition of Mg+−(DME)3 complex via cleavage of C–O bond of one of the three DME molecules indicating irreversible decomposition of DME in the presence of the Mg+ radical. We believe that the data collected as part of this investigation serves as a library of fundamental knowledge towards a deeper understanding of the electrode-electrolyte interfacial reactions.

Second Harmonic Generation for Moisture Monitoring in Dimethoxyethane at a Gold-Solvent Interface Using Plasmonic Structures.

Second harmonic generation (SHG) is forbidden from most bulk metals because metals are characterized by centrosymmetric symmetry. Adsorption or desorption of molecules at the metal interface can break the symmetry and lead to SHG responses. Yet, the response is relatively low, and minute changes occurring at the interface, especially at solid/liquid interfaces, like in battery electrodes are difficult to assess. Herein, we use a plasmonic structure milled in a gold electrode to increase the overall SHG signal from the interface and gain information about small changes occurring at the interface. Using a specific homebuilt cell, we monitor changes at the liquid/electrode interface. Specifically, traces of water in dimethoxyethane (DME) have been detected following changes in the SHG responses from the plasmonic structures. We propose that by plasmonic structures this technique can be used for assessing minute changes occurring at solid/liquid interfaces such as battery electrodes.

Nonaqueous liquid electrolytes based on novel 1-ethyl-3-methylimidazolium bis (nonafluorobutane-1-sulfonyl imidate) ionic liquid for energy storage devices

A new bulky fluorinated anion based ionic liquid, 1-ethyl-3-methylimidazolium bis (nonafluorobutane-1-sulfonyl imidate) (Im1, 3BNFSI), was synthesized through ion exchange condensation process and employed for electrolyte preparation. Nonaqueous liquid electrolytes were prepared using synthesized ionic liquid: lithium bis (nonafluorobutane-1-sulfonyl imidate) salt, propylene carbonate, and dimethoxy ethane solvents by mechanical agitation; and considered for applications in lithium ion batteries. Maximum electrical conductivity 2.21 mS.cm−1 and wide electrochemical stability window (4.3 V) were achieved for the prepared electrolytes using different electrochemical techniques. The highest specific capacity (132.75 mA h.g−1) was achieved for LiFePO4/ionic liquid electrolytes/Li coin cell, suggesting them as an auspicious candidate for high performance lithium ion batteries.

The urinary metabolic profile of diethylene glycol methyl ether and triethylene glycol methyl ether in Sprague-Dawley rats and the role of the metabolite methoxyacetic acid in their toxicity

Ethylene glycol ethers are a well-known series of solvents and hydraulic fluids derived from the reaction of ethylene oxide and monoalcohols. Use of methanol as the alcohol results in a series of mono, di and triethylene glycol methyl ethers. The first in the series, monoethylene glycol methyl ether (EGME or 2-methoxyethanol) is well characterised and metabolises in vivo to methoxyacetic acid (MAA), a known reproductive toxicant. Metabolism data is not available for the di and triethylene glycol ethers (DEGME and TEGME respectively). This study evaluated the metabolism of these two substances in male rats following single oral gavage doses of 500, 1000 and 2000 mg/kg for DEGME and 1000 mg/kg for TEGME. As for EGME, the dominant metabolite of each was the acid metabolite derived by oxidation of the terminal hydroxyl group. Elimination of these metabolites was rapid, with half-lives <4 h for each one. Both substances were also found to produce small amounts of MAA (~0.5% for TEGME and ~1.1% for DEGME at doses of 1000 mg/kg) through cleavage of the ether groups in the molecules. These small amounts of MAA produced can explain the effects seen at high doses in reproductive studies using DEGME and TEGME.

A Layered Inorganic–Organic Open Framework Material as a 4 V Positive Electrode with High‐Rate Performance for K‐Ion Batteries

AbstractK‐ion batteries (KIBs) are promising for large‐scale energy storage owing to various advantages like the high abundance of potassium resources in the Earth's crust, high operational potentials, and high power due to fast diffusion of K+ ions. However, to realize the practical application of KIBs, electrode materials are needed with high operational voltage, good capacity, long cycle life, and low‐cost. This work reports a layered open framework material, K2[(VOHPO4)2(C2O4)], composited with reduced graphene oxide (rGO) as a 4 V positive electrode material for KIBs. The material is prepared by a simple precipitation reaction at room temperature. The material demonstrates reversible K‐extraction/insertion with conventional carbonate ester KPF6 solutions; however, with low specific capacity and low Coulombic efficiency. A high discharge capacity of &gt;100 mAh g−1 with good cycling stability and higher Coulombic efficiency is achieved in a highly concentrated electrolyte, 7 mol kg−1 of potassium bis(fluorosulfonyl)amide (KFSA) in dimethoxyethane (DME) at 0.1 C rate. Due to the facile migration of K+ ions in the framework, the material exhibits excellent rate capability with a discharge capacity of 80 mAh g−1 at 10 C rate, and a good capacity retention of 67% after 500 cycles at 2 C rate.

Using Hmpa As an Additive in Sodium Supercapacitor Electrolyte to Increase Thermal Stability

The development of hybrid electric vehicles (HEV) and portable electronic devices has caused greater demand for high energy and power density devices typically in the form of batteries, but supercapacitors are being integrated into these devices. Supercapacitors boast high power densities (104 W/kg), long cycle lives (>100,000), and simplicity in fabrication. One issue that arises in the practical use of supercapacitors in HEVs is the instability of the electrolyte at elevated temperatures (above 60° C) in the working environment. A number of these sytems use electrolyte systems are unstable at elevated temperaturesr have high vapor pressures that can lead to dangerous conditions for devices. Another concern of supercapacitors is their narrow voltage window that directly affects the overall power density. One novel electrolyte has been discovered that contains sodium hexafluorophosphate (NaPF6) in dimethoxyethane (DME) that boasts a 4V voltage window. The issue arises when this electrolyte is placed at elevated temperatures. PF6 -based salts are well known for quick and irreversible thermal degradation that leads to device failure. This degradation is due to an equilibrium that forms between PF6 - and PF5 - that occurs at elevated temperatures. PF5 - is unstable and will begin to decompose and react with the solvent, impurities, or the electrolyte itself which leads to an autocatalytic degradation reaction. In lithium ion batteries, this issue can be alleviated by the addition of hexamethylphosphoramide (HMPA). HMPA acts as a complexing agent with PF5 -, the thermal decomposition product of NaPF6. This complexing inhibits further decomposition of PF6 - which ultimately increases the thermal stability of the electrolyte. Our work investigates the limitations and advantages of using HMPA as an additive in NAPF6 in DME. A combination of electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) provides enough evidence to prove that NaPF6 in DME does not degrade at elevated temperatures.

Tuning Li2O2 Formation Routes by Facet Engineering of MnO2 Cathode Catalysts

In lithium-oxygen batteries, the solubility of LiO2 intermediates in the electrolyte regulates the formation routes of the Li2O2 discharge product. High-donor-number electrolytes with a high solubility of LiO2 tend to promote the formation of Li2O2 large particles following the solution route, which eventually benefits the cell capacity and cycle life. Here, we propose that facet engineering of cathode catalysts could be another direction in tuning the formation routes of Li2O2. In this work, β-MnO2 crystals with high occupancies of {111} or {100} facets were adopted as cathode catalysts in Li-O2 batteries with a tetra(ethylene)glycol dimethyl ether electrolyte. The {111}-dominated β-MnO2 catalyzed the formation of the Li2O2 discharge product into large toroids following the solution routes, while {100}-dominated β-MnO2 facilitated the formation of Li2O2 thin films through the surface routes. Further computational studies indicate that the different formation routes of Li2O2 could be related to different adsorption energies of LiO2 on the two facets of β-MnO2. Our results demonstrate that facet engineering of cathode catalysts could be a new way to tune the formation route of Li2O2 in a low-donor-number electrolyte. We anticipate that this new finding would offer more choices for the design of lithium-oxygen batteries with high capacities and ultimately a long cycle life.

Dielectric relaxation and hydrogen bonding interaction of polyethylene glycol dimethyl ether in water mixture

ABSTRACT The complex permittivity spectra of binary mixtures of polyethylene glycol dimethylether [PEGDME: Molecular Weight 250 g.mol−1 & 500 g.mol−1] with water over entire concentrations and at different temperatures (5ºC, 15ºC and 25ºC) have been measured using time domain reflectometry (TDR) technique in the frequency range of 10–30 GHz. The complex permittivity spectra were fitted in Cole–Davidson model using non-linear least square fit method. The dielectric parameters, such as static dielectric constant and relaxation time, have been determined for PEGDME250+ water and PEGDME500+ water mixtures. The hydrogen bonding interactions for the PEGDME250- water & PEGDME500- water mixtures have been discussed through the determination of excess permittivity, Bruggemann factor and thermodynamic parameters.

Understanding the Effect of UV-Induced Cross-Linking on the Physicochemical Properties of Highly Performing PEO/LiTFSI-Based Polymer Electrolytes.

We report a thorough, multitechnique investigation of the structure and transport properties of a UV-cross-linked polymer electrolyte based on poly(ethylene oxide), tetra(ethylene glycol)dimethyl ether (G4), and lithium bis(trifluoromethane)sulfonimide. The properties of the cross-linked polymer electrolyte are compared to those of a non-cross-linked sample of same composition. The effect of UV-induced cross-linking on the physico/chemical characteristics is evaluated by X-ray diffraction, differential scanning calorimetry, shear rheology, 1H and 7Li magic angle spinning nuclear magnetic resonance (NMR) spectroscopy, 19F and 7Li pulsed field gradient stimulated echo NMR analyses, electrochemical impedance spectroscopy, and Fourier transform Raman spectroscopy. Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number (>0.5) and ionic conductivity (>0.1 mS cm?1) at ambient temperature, by tailoring the structural/morphological characteristics of the polymer matrix. Finally, the polymer electrolyte allows reversible operation with stable profile for hundreds of cycles upon galvanostatic test at ambient temperature of LiFePO4-based lithium-metal cells, which deliver full capacity at 0.05 or 0.1C current rate and keep high rate capabilities up to 1C. This enforces the role of UV-induced cross-linking in achieving excellent electrochemical characteristics, exploiting a practical, easy up-scalable process.

Enhanced ionic conductivity and interface stability of hybrid solid-state polymer electrolyte for rechargeable lithium metal batteries

Compared to conventional organic liquid electrolyte, solid-state polymer electrolytes are extensively considered as an alternative candidate for next generation high-energy batteries because of their high safety, non-leakage and electrochemical stability with the metallic lithium (Li) anode. However, solid-state polymer electrolytes generally show low ionic conductivity and high interfacial impedance to electrodes. Here we report a hybrid solid-state electrolyte, presenting an ultra-high ionic conductivity of 3.27 mS cm−1 at room temperature, a wide electrochemical stability window of 4.9 V, and non-flammability. This electrolyte consists of a polymer blend matrix (polyethylene oxide and poly (vinylidene fluoride-co-hexafluoropropylene)), Li+ conductive ceramic filler (Li1.5Al0.5Ge1.5(PO4)3) and a solvate ionic liquid (LiFSI in tetra ethylene glycol dimethyl ether, 1:1 in molar ratio) as plasticizer. The introduction of the solvate ionic liquid to the solid-state electrolyte not only improves its ionic conductivity but also remarkably enhances the stability of the interface with Li anode. When applied in Li metal batteries, a Li|Li symmetric cell can operate stably over 800 h with a minimal polarization of 25 mV and a full Li|LiFePO4 cell delivers a high specific capacity of 158 mAh g−1 after 100 cycles at room temperature.

In situ Raman spectroscopic analysis of solvent co-intercalation behavior into a solid electrolyte interphase-covered graphite electrode

Solid electrolyte interphase (SEI) on a graphite-negative electrode plays an important role in lithium-ion batteries. The roles of the SEI involve a passivation of a solvent co-intercalation reaction, but why the SEI can suppress the solvent co-intercalation reaction is not fully understood. In this study, the solvent co-intercalation behavior against various SEI-covered graphite electrodes was investigated using cyclic voltammetry and in situ Raman spectroscopy. Ethylene carbonate (EC)-treated, vinylene carbonate (VC)-treated, and untreated graphite electrodes were compared in a dimethoxyethane (DME)-based electrolyte solution. Whereas the DME co-intercalation constantly proceeded from 1.2 to 0.6 V versus Li/Li+ for the untreated graphite electrode, the co-intercalation was relatively suppressed above 0.8 V versus Li/Li+ for the EC-treated and VC-treated graphite electrodes. Below 0.7 V versus Li/Li+, the VC-treated electrode exhibited higher passivation ability than the EC-treated one. In addition, the co-intercalation behavior in electrolyte solutions containing an SEI-reagent in advance was also investigated. In this case, the passivation ability was further improved.

Transparent Conducting Oxides As Cathodes in Li-O2 batteries: A First Principles Computational Investigation

Li-O2batteries have traditionally used carbon based electrodes (graphite, buckypaper) as the cathode of choice due to its good electrical conductivity, stability against non-aqueous electrolytes like dimethoxyethane (DME) and ease of handling. But, the carbon cathode also leads to formation of carbonate by-products that increase overpotentials during charging leading to degradation of the cathode and reduction of cyclability. Recent investigations have focused on using metal-oxides like SnO2, TiO2 as viable cathodes-alternatives in Li-O2 systems. In this paper, we investigate transparent conducting oxides (TCOs) as cathodes with focus on the interface between the TCO surfaces and the discharge product, Li2O2, in the Li-O2battery using first principles computations. TCOs have found use as electrodes in photovoltaic cells and other semi-conductor applications due to their tunable conductivity via defects/doping, ease of synthesis of preferred surfaces and stability to environmental factors. These properties, along with their stability against ethers, make them a promising class of cathodes in Li-O2 battery. Using DFT computations and thermodynamic arguments, we predict the chemical and electrochemical stability of some of the well-known TCOs in a Li-O2 battery. Further, surface adsorption computations show that not all oxides promote formation of Li2O2 and different surfaces of same cathode material can behave differently. We also explore the role dopants can play in achieving a stable electrically conducting cathode that promotes discharge of Li2O2. We extend the analysis to suggest possible oxide chemistries that should be investigated as cathodes in Li-O2batteries.

A comprehensive insight into the volumetric response of graphite electrodes upon sodium co-intercalation in ether-based electrolytes

In this study, the interplay between the electrochemical behavior, structural modifications and volumetric changes of graphite-based negative electrodes for sodium ion batteries is evaluated. The electrolyte solvents chosen for this study are ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TriGDME), and tetraethylene glycol dimethyl ether (TEGDME) while the salt is sodium trifluoromethanesulfonate (NaOTf). The volume changes undergone upon co-(de)intercalation of the [Na-solvent]+ complexes are systematically investigated by means of in situ electrochemical dilatometry and correlated to the structural modification of the graphite crystalline lattice as detected by in situ X-ray diffraction. The expected staging mechanism upon co-intercalation, leading to the formation of stage-I graphite intercalation compound, is observed with all electrolytes. However, the various solvents play a substantial role on the reversibility of such structural changes in the first cycle. The effect of temperature is also investigated showing that the most stable electrochemical performance is observed with the TEGDME at room temperature, but with TriGDME at higher temperatures. Nonetheless, post-mortem scanning electron microscopy suggests that the surface layer forming after the first sodiation may dissolve in the following de-sodiation.

Effect of Some Oxygenates on the Opacity Level of a DI Diesel Engine with and without DPF

Toyota car fitted with smoke meter to measure the opacity in the exhaust was used. Five different types of oxygenates were used with the concentration of each one varied between 5 to 20% by volume at an increment of 5%.&#x0D; &#x0D; The results show a significant reduction in the opacity of the exhaust products. A maximum of 70% reduction was achieved when 15% ethanol was added at 3000 RPM, and 62% reduction when 20% methanol was added at same speed. As for Dimethoxy Ethane (DMET), a maximum reduction of 30% was achieved at 3000 RPM and that of Tri-propylene glycol methyl ether (TPGME) was 27.3% at same speed. Diethylene glycol monoethyl ether (DGME) did not show encouraging results as a maximum reduction of 10.3% was achieved at 2000 RPM with 5% of DGME. Further, it was found that the reduction in the opacity level was less significant when the filter was used. This, perhaps, is due to the nature of the DPF used.

(Keynote) Updates in Non-Aqueous Mg Electrochemistry, Biu Corner.

Developing practical rechargeable magnesium batteries (RMB) is very attractive. The first rechargeable magnesium battery prototype was demonstrated almost two decade ago. It comprised magnesium metal anode, Mo6S8 Chevrel phase cathode, and complex ethereal solutions that included THF or glymes and ionic organo-metallic species formed by complicated reactions between a RnMgCl2-n Lewis base and an AlClnR3-n Lewis acid (R = alkyl or aryl groups). These prototypes exhibited very prolonged cycle life at 100% cycling efficiency (no side reactions). However the low abundance of molybdenum and the low energy density (1.1V, 120mAh/g cathode capacity) avoided any practical development of these first systems. Unfortunately, we are not aware of any practically promising RMB that that could show better electrochemical performance that the 19 years old first prototype. A main challenge related to Mg anodes is that they cannot behave reversibly if they are covered by surface films (no relevance for the SEI model). This challenge was met quite well over the years, since several families of solutions where developed, possessing high anodic stability, in which Mg metal anodes are surface films free, behave quite reversibly. Matching appropriate, attractive enough cathodes to the reversible Mg/electrolyte solutions couples remained the big, unresolved yet, challenge. Hence, the main difficulty in the realization of RMB starts from the tendency of the reactive Mg anodes to form surface films on their surface that block reversible Mg ions migration through them. Therefore, RMB have to operate in a non-reducing environment, namely ethereal solutions and Mg salts which anions are not reduced by Mg metal to form passivating surface species. These limitations reduce considerably the choice of relevant cathode materials for high energy density RMB. These constraints force us to concentrate in recent years in fundamental aspects of non-aqueous magnesium electrochemistry. MgTFSI2 is currently one of the only readily ether soluble salts which anion is not readily reduced by Mg metal. However the electrochemical performance of ethers/MgTFSI2 is poor. Surprisingly we proved that in DME (1,2 di methoxy ethane), this salt fully disassociates and forms 3DME-Mg2+ cations with a rigid structure.1 These solutions exhibit a very unique thermodynamic behavior as will be described. The solvent-solvate bonds are too strong to allow reversible Mg deposition in DME/MgTFSI2 solutions. Adding MgCl2 to these solutions changes there structure and improves remarkably their electrochemical performance.2 The main ionic species therein are [Mg2(μ-Cl)2(DME)4] 2+ cations and completely un-coordinate 2TFSI- anions for the 1:1 MgCl2:MgTFSI2 ratio, and [Mg3(μ-Cl)4(DME)5] 2+ cations and un-coordinate 2TFSI- anions for the 1:2 MgCl2:MgTFSI2 ratio. The formation of "softer" complex cations in the presence of MgCl2 is the reason for the improved electrochemical activity.3 Turning to the cathode side - V2O5 is the most studied cathode material in connection to Mg batteries mainly due to its high theoretical specific capacity, of 441 mAh g1 (for 3e-/unit discharge) and its proven capability to intercalate Mg ions. However the vast majority of studies could not meet need to couple to this important cathode material electrolyte solutions in which Mg electrodes behave reversibly. We demonstrated that although Mg ions intercalation into V2O5 electrodes occurs from acetonitrile solutions (not suitable for Mg anodes), addition of an ether solvent such as DME to these solutions dramatically slows down the Mg ions insertion kinetics into V2O5 electrodes due to strong solvent-cation interactions. 4 Another important cathode material that was explored in connection with RMB is Sulfur. This cathode material is very attractive in terms of capacity and cost, thus a lot of efforts are invested in developing Mg-S batteries. We have shown that polysulfide species dissolution during discharge of sulfur cathodes in Mg-S cells leads to a severe blockage of the Mg anodes Due to formation of surface films comprising Mg sulfides moieties. Therefore in any practical Ng-S batteries, avoiding polysulfide species dissolution is mandatory.4

Probing the Interactions and Dynamics in an Ionic Liquid – Organic Solvent Hybrid Electrolyte System for Potential Application in Li-S Batteries

The depletion of fossil fuel and strict environmental regulation on carbon footprints has prompted a greater reliability on sustainable energy sources. Batteries represent an important energy storage option due to their wide range of applicability and portability, however, for certain applications such as transportation, a higher energy density battery is required. Beyond the conventional Li-ion battery system, current research is focusing on next-generation cost effective devices. Amongst them, the Li-S battery technology is very promising due to its high theoretical capacity and energy density [1]. However, the chemistry involved in the Li-S battery is a complex process with multiple consecutive electrochemical reactions. Despite having many advantages, its application is still limited by several issues, e.g., the dissolution and diffusion of intermediate polysulphides, unstable plating and stripping of Li metal, both resulting in rapid capacity fading [2]. Previously, we reported the application of a novel electrolyte system composed of N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide, C3mpyrFSI, ionic liquid (IL) and 1,2 dimethoxyethane (DME) in the presence of varying saturated lithium bis(fluorosulfonyl)imide, LiFSI which predominantly suppressed the polysulphide dissolution and diffusion while showing improved lithium plating and stripping behavior [3]. In order to expand our understanding on the role of DME and the lithium salt concentration; in this work, we have considered a similar ionic liquid based electrolyte system but at a constant concentration of LiFSI salt. The ionic interactions among different species of the electrolyte system have been extensively studied by nuclear magnetic resonance (NMR) spectroscopy using 1D chemical shift, PFG-NMR and Heteronuclear Overhauser Effect SpectroscopY (HOESY) measurements. We found that, when increasing the DME concentration in the system, a strong association of Li+ cation with the DME occurs due to the electronegative oxygen atoms present in the DME molecules which leads to strong coordination. This leads to a change of the chemical shift of 7Li nuclei due to them being increasingly de-shielded. Interestingly, we found that the diffusivity of both Li+ and DME species are very similar, which also confirms that a Li-DME complex is present with FSI anion associated in the next coordination sphere to counterbalance the positively charged Li complex. MD simulations are underway to better elucidate the molecular shell structure of the system. We have also carried out electrochemical characterizations of these hybrid electrolytes to determine their potential applicability in a lithium sulphur battery. It was apparent using cyclic voltammogram (CV) performed in a three electrode set-up, that an increasing amount of DME increases the ionic conductivity but decreases the lithium plating-stripping efficiency. A coin-cell study of Li/Li symmetrical cycling showed an excellent plating-stripping behaviour for 70%IL-30%DME composition. We have carried out a full cell cycling against sulphur cathode and the optimised electrolyte composition obtained a promising first discharge capacity of 1100mAh/g. Additionally, we have investigated the sulphur speciation in the presence of this ionic liquid in a three-electrode system where platinum mesh has been used as working electrode coupled with in-situ UV-vis spectroscopy. Finally, a time dependent bulk electrolysis study revealed the plausible intermediates formed during the charge-discharge cycle of sulphur redox reaction. From these studies it appears that the composition of this novel hybrid electrolyte system can be tuned to provide a system with improved transport, electrochemical and sulphur speciation properties which lend themselves to a higher performance, next generation lithium sulphur battery technology.

Influence of various cosolvents on the calcium oxide-catalyzed ethanolysis of sunflower oil

Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-hexane, triethylamine, ethylene glycol dimethyl ether, glycerol, tetrahydrofuran and dioxane) were applied as cosolvents in the CaO-catalyzed ethanolysis of sunflower oil performed in a batch stirred reactor under the following reaction conditions: temperature 70 ?C, ethanol-to-oil mole ratio 12:1, initial catalyst concentration 1.374 mol?L-1 and amount of cosolvent 20 % based on the oil amount. The main goals were to assess the effect of the used cosolvents on the synthesis of fatty acid ethyl esters (FAEE) and to select the most efficient one with respect to the final FAEE content, reaction duration and safety profile. In the absence of any cosolvent, the reaction was rather slow, providing a FAEE content of only 89.7?1.7 % after 4 h. Of the tested cosolvents, diethanolamine, triethanolamine and ethylene glycol significantly accelerated the ethanolysis reaction, whereby the last two provided a final FAEE content of 93.1?2.1 and 94.1?1.5 %, respectively, within 0.5 h. However, because of its safety profile, triethanolamine was selected as the best cosolvent for the ethanolysis of sunflower oil catalyzed by calcined CaO.

Trace level analysis of three glycol ethers in wood stains by APCI-LC-MS/MS

A direct injection liquid chromatography tandem atmospheric pressure chemical ionization mass spectrometry method was developed for determination of diethylene glycol methyl ether, dipropylene glycol butyl ether, and dipropylene glycol methyl ether.