Optimization and characterization of ionic liquid based electrolytes for Li-ion batteries

U ovoj doktorskoj disertaciji ispitivani su elektroliti na bazi jonskih tečnosti pogodni za primenu u litijum  jonskim baterijama. Fizičko-hemijska svojstva binarnih smeša jonskih tečnosti sa dicijanamidnim i bis(trifluorometilsulfonil)imidnim anjonima i molekulskih rastvarača ispitana su u celom opsegu molskih udela i na različitim temperaturama. Na osnovu izmerenih gustina, viskoznosti i električne provodljivosti izračunati su različiti fizičko hemijski parametri i diskutavne interakcije između komponenata smeša. Ispitana je termička i elektrohemijska stabilnost odabranih elektrolita. Dodatkom litijumove soli u odabrane binarne smeše dobijeni su ternarni sistemi koji su okarakterisani u zavisnoti od koncentracije litijumove soli. Odabrani elektroliti upotrebljeni su za  ispitivanje performansi litijum  jonske ćelije sa anatas TiO2  nanotubularnim elektrodama.Cikličnom voltametrijom i galvanostatskim cikliranjem su ispitane performanse ćelije u toku 150 ciklusa punjenja i pražnjenja. Na osnovu ciklovoltametrijskih merenja izračunati su koeficijenti difuzije i energija aktivacije za difuziju.In this doctoral dissertation, Ion liquid-based electrolytes were tested for use in  lithium-ion batteries. The physicochemical properties of binary mixtures of ionic  liquids with dicyanamide and bis (trifluoromethylsulfonyl) imide anions and  molecular solvents were examined throughout the range of molar proportions and at different temperatures. Based on the measured densities, viscosity and electrical conductivity, various physical chemical parameters and discrete interactions between  the components of the mixture are calculated. Thermal and electrochemical stability of selected electrolytes was examined. By addition of lithium salt to the selected binary mixtures, ternary systems were characterized which were characterized by the concentration of lithium salt. The selected electrolytes were used to test the performance of the lithium-ion cell with anatomic TiO2 nanotubular electrodes. Cyclic voltammetry and galvanostatic cycling tested the cell's performance during the 150 charge and discharge  cycles. Based on cyclotoltametric  measurements, the diffusion coefficients and activation energies for diffusion were calculated

Wear of diamond-coated cutting tool inserts upon machining of Al-12% Si and glass fiber/polyester resin composites

Results of the wear resistance of the diamond-coated cutting tool inserts upon machining Al-12% Si alloy and glass fiber/polyester resin composites are presented in this paper. The aim of this paper was to demonstrate the advantages of application of cutting tool inserts with the diamond coating over the conventional tungsten-carbide (WC) tools, and to obtain the cheaper serial production (shorter machining time) and satisfactory lifetime of the diamond cutting tool inserts. Surface roughness of the machined samples was measured for both as-received and diamond coated inserts. The diamond microstructure of undamaged part of inserts as well as the appearance of microstructure of diamond coated inserts after machining has been investigated. Results of the behavior of two regimes of preparation of diamond-coated inserts were compared and analyzed. Generally, the wear resistance of the diamond-coated cutting tool is superior over the conventional tool

Mutually Beneficial Combination of Molecular Dynamics Computer Simulations and Scattering Experiments

We showcase the combination of experimental neutron scattering data and molecular dynamics (MD) simulations for exemplary phospholipid membrane systems. Neutron and X-ray reflectometry and small-angle scattering measurements are determined by the scattering length density profile in real space, but it is not usually possible to retrieve this profile unambiguously from the data alone. MD simulations predict these density profiles, but they require experimental control. Both issues can be addressed simultaneously by cross-validating scattering data and MD results. The strengths and weaknesses of each technique are discussed in detail with the aim of optimizing the opportunities provided by this combination

Optimization and characterization of ionic liquid based electrolytes for Li-ion batteries

U ovoj doktorskoj disertaciji ispitivani su elektroliti na bazi jonskih tečnosti pogodni za primenu u litijum  jonskim baterijama. Fizičko-hemijska svojstva binarnih smeša jonskih tečnosti sa dicijanamidnim i bis(trifluorometilsulfonil)imidnim anjonima i molekulskih rastvarača ispitana su u celom opsegu molskih udela i na različitim temperaturama. Na osnovu izmerenih gustina, viskoznosti i električne provodljivosti izračunati su različiti fizičko hemijski parametri i diskutavne interakcije između komponenata smeša. Ispitana je termička i elektrohemijska stabilnost odabranih elektrolita. Dodatkom litijumove soli u odabrane binarne smeše dobijeni su ternarni sistemi koji su okarakterisani u zavisnoti od koncentracije litijumove soli. Odabrani elektroliti upotrebljeni su za  ispitivanje performansi litijum  jonske ćelije sa anatas TiO2  nanotubularnim elektrodama.Cikličnom voltametrijom i galvanostatskim cikliranjem su ispitane performanse ćelije u toku 150 ciklusa punjenja i pražnjenja. Na osnovu ciklovoltametrijskih merenja izračunati su koeficijenti difuzije i energija aktivacije za difuziju.In this doctoral dissertation, Ion liquid-based electrolytes were tested for use in  lithium-ion batteries. The physicochemical properties of binary mixtures of ionic  liquids with dicyanamide and bis (trifluoromethylsulfonyl) imide anions and  molecular solvents were examined throughout the range of molar proportions and at different temperatures. Based on the measured densities, viscosity and electrical conductivity, various physical chemical parameters and discrete interactions between  the components of the mixture are calculated. Thermal and electrochemical stability of selected electrolytes was examined. By addition of lithium salt to the selected binary mixtures, ternary systems were characterized which were characterized by the concentration of lithium salt. The selected electrolytes were used to test the performance of the lithium-ion cell with anatomic TiO2 nanotubular electrodes. Cyclic voltammetry and galvanostatic cycling tested the cell's performance during the 150 charge and discharge  cycles. Based on cyclotoltametric  measurements, the diffusion coefficients and activation energies for diffusion were calculated

The salting-out effect and impact of temperature on phase diagrams of aqueous biphasic systems based on novel synthesized dicyanamide ionic liquids

Pod jonskim tečnostima (JT) se podrazumevaju jonska jedinjenja koja su tečna na temperaturama ispod 100°C. Među brojnim zanimljivim svojstvima koje poseduju hidrofilne jonske tečnosti je i njihova sposobnost da grade dvofazne vodene sisteme u kombinaciji sa neorganskim ili organskim solima. U ovom radu su određeni i okarakterisani fazni dijagrami (binodalne krive) za ispitivane bifazne vodene sisteme {JT + neorganska so +H2O} za dve novosintetisane jonske tečnosti: 1-etil-3-etilimidazolijum-dicijanamid [1-C23-C2im][DCA] i 1-butil-3-etilimidazolijum-dicijanamid [1-C43-C2im][DCA] u kombinaciji sa neorganskim solima: K3PO4 i K2CO3. Eksperimentalni rezultati su fitovani na osnovu Merchuk-ove jednačine i pokazuju da priroda jonske tečnosti kao i neorganske soli utiču u velikoj meri na formiranje bifaznih vodenih sistema. Pokazano je da K3PO4 ima veću sposobnost za građenje bifaznih sistema od K2CO3, što je posledica veće entropije hidratacije anjona. Povećanje bočnog niza na imidazolijum jonu dovodi do lakšeg indukovanja bifaznih sistema tj. potrebna je manja količina neorganske soli da bi se nagradile dve faze. Uticaj temperature na formiranje bifaznih vodenih sistema postoji i dvofazna oblast se povećava sa snižavanjem temperature.Ionic liquids (IL) are ionic compounds which are liquid below 100 °C. One of many interesting features of ionic liquids miscible with water near room temperature is that they can induce ionic-liquid-based aqueous biphasic system (ABS) in combination with inorganic/organic salts. In this work, phase diagrams for aqueous solutions of 1-ethyl-3-ethylimidazolium-dicyanamide [1-C23-C2im][DCA] and 1-butyl-3-ethylimidazolium- dicyanamide [1-C43-C2im][DCA] based ILs combined with phosphate and carbonate-based salts, K3PO4 and K2CO3, are reported and discussed. Merchuk equation was applied in order to correlate the experimental binodal data. It was found that K3PO4 has better salting-out ability to induce aqueous biphasic system than K2CO3 because of higher hydration entropy. The cation influence on the ability to form ABS is investigated for the IL with the same anion, dicyanamide [DCA]- and various alkyl chain lengths. It was found that ability to form ABS increases with the increase of the alkyl chain length on the imidazolium ion because of increasing ionic liquid hydrophobicity and poorer affinity for water. The experimental results also show that biphasic region expands with reduction of temperature.53. Savetovanje Srpskog hemijskog društva : Program i kratki izvodi radova : Kragujevac, Srbija, 29. i 30. maj 2015

The salting-out effect and impact of temperature on phase diagrams of aqueous biphasic systems based on novel synthesized dicyanamide ionic liquids

Pod jonskim tečnostima (JT) se podrazumevaju jonska jedinjenja koja su tečna na temperaturama ispod 100°C.1 Jonske tečnosti se sastoje od velikih, asimetričnih organskih katjona (amonijum, fosfonijum, sulfonijum, imidazolijum, piridinijum, pirolidinijum itd.) i manjih organskih ili neorganskih anjona (bromid, hlorid, dicijanamid, metansulfonat, tetrafluoroborat itd.). Dimenzije i oblik samih jona, pre svega katjona, onemogućavaju njihovo „gusto“ pakovanje i obrazovanje jonske kristalne strukture, čime se objašnjava niska temperatura topljenja i tečno agregatno stanje ovih sistema na sobnoj temperaturi.2,3 Jonske tečnosti poseduju niz jedinstvenih svojstva kao što su zanemarljiv napon pare, hemijska i termalna stabilnost, širok elektrohemijski prozor, visoku provodljivost, veliki toplotni kapacitet, podesivu hemijsku strukturu i fizičke osobine i jaku sposobnost solvatacije.4 Jonske tečnosti su ekološki prihvatljivija i pogodna alternativa isparljivim i toksičnim organskim rastvaračima. Među brojnim zanimljivim svojstvima koje poseduju hidrofilne jonske tečnosti je i njihova sposobnost da grade dvofazne vodene sisteme u kombinaciji sa neorganskim ili organskim solima. Naime, dodatak neorganske soli u vodeni rastvor jonske tečnosti uzrokuje razdvajanje tečnih faza i formiranje dvofaznog vodenog sistema.5 Bifazni vodeni sistemi mogu biti značajni pri recikliranju ili koncentrovanju hidrofilnih jonskih tečnosti iz vodenih rastvora, zatim u reakciji metateze pri sintezi novih jonskih tečnosti, a od naročitog su interesa u separacionoj hemiji. Izborom adekvatnih komponenata (jonske tečnosti i neorganske/organske soli) i jednostavnom manipulacijom sastava faza može se postići visoka selektivnost i željeni koeficijent raspodele za ekstrakciju velikog broja jedinjenja kao što su alkaloidi, lekovi, aminokiseline, proteini, hormoni, alkoholi, aromatična i fenolna jedinjenja itd.6 Ispitivanje faznih dijagrama dvofaznih vodenih sistema sa jonskim tečnostima predstavlja prvu fazu u optimizaciji uslova za ekstrakciju određenog jedinjenja. Cilj ovog rada je da se odrede ravnotežni dijagrami dvofaznih vodenih sistema {JT + neorganska so + + H2O} za novosintetisane jonske tečnosti 1-etil-3-etilimidazolijum-dicijanamid [1-C23-C2im][DCA] i 1-butil-3-etilimidazolijum-dicijanamid [1-C43-C2im][DCA] i da se ispitaju uticaji jonske tečnosti, neorgaske soli i temperature na mogućnost formiranja bifaznih vodenih sistema.In this work, novel phase diagrams for aqueous solutions of 1-ethyl-3-ethylimidazolium dicyanamide [1-C23- C2im][DCA] and 1-butyl-3-ethylimidazolium dicyanamide [1-C43-C2im][DCA] -based ionic liquids (ILs) combined with phosphate and carbonate based salts, K3PO4 and K2CO3, are reported and discussed. Merchuk equation was applied in order to correlate the experimental binodal data. It was found that K3PO4 has better salting-out ability to induce aqueous biphasic system (ABS) than K2CO3. The cation influence on the ability to form ABS is investigated for the IL with the same anion, dicyanamide [DCA]- and various alkyl chain lengths in the imidazolium N-1 position. It was found that ability to form ABS increases with the increase of the alkyl chain length on the imidazolium cation because of increasing ionic liquid hydrophobicity and poorer affinity for water. The effect of temperature and the alkyl chain length of ionic liquid on two phase formation were investigated. The experimental results show that biphasic region expands with reduction in temperature.53. savetovanje Srpskog hemijskog društva : knjiga radova; 10-11. jun 2016; Kragujevac / 53rd Meeting of the Serbian Chemical Society : Proceedings; June 10-11, 2016; Kragujeva

Effect of the substrate material on diamond CVD coating properties

Diamond coatings were deposited onto different substrates (Cu, Si, WC-Co, Mo) by hot-filament chemical vapor deposition (CVD). Characterization of the obtained coatings was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, Raman spectroscopy and Fourier transform infrared reflection (FTIR) spectroscopy. The results and observed differences are discussed from the aspect of the chemical nature of the substrate and its reactivity with a gaseous medium. 2003 Elsevier Science B.V. All rights reserved

Simultaneous extraction of pesticides of different polarity applying aqueous biphasic systems based on ionic liquids

In this paper we report a simultaneous one-step extraction of five pesticides (acetamiprid, imidaclopride, simazine, linuron and tebufenozide) of different polarity using aqueous biphasic system based on 1-butyl-3(methyl or ethyl) substituted imidazolium or pyrrolidinium ionic liquids with bromide or dicyanamide anion and potassium carbonate as a salting-out agent. Experimentally data obtained for the ternary system (ionic liquid + K2CO3 + H2O) were fitted and correlated by Merchuk equation with satisfactory high correlation factor. The effect of the cation alkyl chain length and the variation of anions of the ionic liquid on the aqueous biphasic system formation and the efficiency of pesticide extraction were investigated. Complete extraction of all studied pesticides was obtained applying aqueous biphasic system based on 1-butyl-3-ethyl imidazolium dicyanamide. It was shown that simultaneous extraction of the different polarity pesticides is achieved in a single-step procedure applying properly tailored ionic liquids in the aqueous biphasic system formulation. In order to explain excellent extraction of the polar pesticides in the studied aqueous biphasic systems, molecular dynamics was applied and the binding energies and non-covalent interactions were calculated. It was found that 1-butyl-3-ethyl imidazolium dicyanamide achieves the strongest interactions with the polar pesticides (acetamiprid and imidaclopride) leading to the highest partition coefficients. It was shown that combination of experimental and computational approach can be successfully applied for the selection and design of suitable ionic liquids for efficient extraction of various polarity pesticides using simple aqueous biphasic ionic liquid based systems. (C) 2017 Elsevier B.V. All rights reserved

Influence of the alkyl chain length on densities and volumetric properties of 1,3-dialkylimidazolium bromide ionic liquids and their aqueous solutions

In this manuscript eight new 1,3-dialkylimidazolium bromide ionic liquids, {[}CnCmim]{[}Br], were synthesized and characterized. Densities of ionic liquids and their diluted aqueous solutions have been measured over the whole composition range at selected temperatures from (293.15 to 323.15) K and at atmospheric pressure (p = 0.1 MPa). Influence of alkyl chain length and cation symmetry on densities and volumetric properties as well as nature of the interactions in aqueous {[}CnCmim]{[}Br] solutions have been discussed and compared with previously published aqueous {[}C(2)C(4)im]{[}Br] system. Densities of pure bromide based ionic liquids decrease with increasing alkyl chain length on imidazolium cation and depend on total number of methyl group in both side alkyl chains. Apparent molar volumes at infinite dilution of investigated ionic liquids in water increase linearly with increase of the total number of the C atoms in the side alkyl chain. (C) 2018 Elsevier Ltd

Aqueous biphasic system formation using 1-alkyl-3-ethylimidazolium bromide ionic liquids as new extractants

In this work three 1-alkyl-3-ethylimidazolium bromide ionic liquids (alkyl = ethyl, hexyl and octyl) were synthesized applying both, conventional and microwave assisted synthetic paths. The phase diagrams for aqueous solutions of 1-alkyl-3-ethylimidazolium bromide ionic liquids as novel extractants combined with phosphate-based salts are reported and discussed in terms of aqueous biphasic system (ABS) formation. Merchuk equation was applied in order to correlate the,experimental binodal data. The liquid-liquid equilibrium data (tie-line compositions and tie-line length) were also experimentally determined by a gravimetric method. The influence of the alkyl chain length on ABS formation ability was investigated. It was found that ability to form ABS increases with the increase of the alkyl chain length on the imidazolium cation. Also, it was found that ionic liquids with ethyl group in the N-3 position better form ABS compared to those with methyl substituent. This was discussed in terms of increasing ionic liquid hydrophobicity and poor affinity for water. In order to better understand the impact of the alkyl side chain of the imidazolium ion and the efficiency of ABS formation, computer simulations were performed using investigated ionic liquids with the ethyl group in the position N-3 of the cation and different alkyl substituents in the position N-1. Also, extraction of selected organic dyes was performed to demonstrate application of studied ionic liquids as novel extractants. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved