Cette thèse a pour objectif l’étude et la mise au point d’un procédé de fabrication, par cristallisation, de sel thermal enrichi en magnésium, à partir d’eaux minérales naturelles chlorurées sodiques fortes. Un modèle dynamique a d’abord été développé pour la simulation du procédé. Ce modèle est basé sur la description des phénomènes physico-chimiques intervenant dans les équilibres thermodynamiques multiphasiques (liquide, vapeur, solides). Puis, un pilote de laboratoire a été mis en place pour vérifier la faisabilité du procédé et valider le modèle développé. Le pilote proposé est constitué de deux réacteurs en série entre lesquels est placé un système de filtration. Une étude expérimentale et par modélisation du procédé avec l’eau thermale de Salies-de-Béarn a ensuite été réalisée. Cette étude montre qu’il est possible de produire un sel thermal ou une eau-mère naturellement enrichis en magnésium. / The aim of this thesis is the study and the development of a production process, by cristallization, of thermal salt enriched in magnesium, from highly chlorinated natural waters. At first, a dynamic model was developed for the process simulation. This model is based on the description of physical-chemical phenomena occurring in multiphase thermodynamic equilibrium (liquid, vapor, solids). Then, a laboratory pilot was set up to check the process feasibility and to validate the developed model. The proposed pilot is a series of two reactors between which is placed a filtration system. Finally, an experimental and modeling study of the process has been realized with thermal water of Salies-de-Béarn as raw-material. This study shows that it is possible to produce a thermal salt or mother liquor naturally enriched in magnesium.

Room temperature molten liquids are proposed to be good alternates for volatile and harmful organic compounds. They are useful in varied areas of applications ranging from synthesis, catalysis to energy storage molten electrolytes have certain unique characteristics such as low vapour pressure, reasonably high ionic conductivity, high thermal stability and wide electrochemical window. These molten liquids can be classified in to two types depending on the nature of the species present in the liquids. One, those liquids consists only of ions (e.g) conventional imidazolium based ionic liquids and other that consists of ions and solvents (e g) acetamide eutectics. Acetamide and its eutectics from room temperature molten solvents that is unique with interesting physicochemical properties. The solvent properties of molten acetamide are similar to water, with high dielectric consist of 60 at 353 k. its acid – base properties are also similar to water, and it can solublise variety of organic and inorganic compounds as well. in the present studies room temperature molten liquids consisting of acetamide as one of the components have been prepared and used for various applications. Room temperature molten electrolytes consisting of magnesium perchlorate/magnesium triflate as one of the constituents have been used for rechargeable magnesium batteries where as those consisting of zinc perchlorate /zinc triflate have been used for zinc based rechargeable batteries. Full utilization of cathode material (y-mno2) is achieved using amide-based molten liquid as electrolyte in rechargeable zinc based batteries. Ammonium nitrate/ lithium nitrate containing electrolytes have been used for electrochemical super capacitors. They have been used as solvent cum stabilizers for metallic nanochains that can be used as substrate in surface enchanced Raman scattering studies.

No description available.

The thesis is devoted to the field of properties investigation of new types of electrolytes, and assess the appropriateness of electrolytes studied in this paper for use in Li -ion batteries. It focuses specifically on electrolytes based on aprotic solvents and their mixtures with the flame retardants. The goal of the thesis is to investigate the effects of FRAs on electrolyte mixtures via changes in specific conductivity and freezing point. These objectives were fulfilled by using electrochemical impedance spectroscopy in combination with a cryoscopic measurement method. There were overall 16 samples examined. The samples were prepared as a combination of chemicals, specifically Ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), dimethyl sulfone (DMSO2), triethyl phosphate (TEP) Dimethyl methylphosphonate (DMMP), triphenyl phosphate (TPP). Based on the results of the experiments, the mixtures were sorted according to the observed properties in the tables listed in the last part of this paper. These values can be further used to supplement the continuing research of electrolytes and also as assistance in searching for the new electrolyte mixtures.

Department of Chemistry / As an alternative energy source, lithium ion batteries have become increasingly important with a wide range of applications in industry, and many international companies are investing in this big project. This study was aimed at the development of safer lithium-ion power sources by using new organic additives to overcome the possible safety problems. In this study, the conformations and energies of several synthesized boronates were investigated through computational study using density functional theory (DFT) with the Becke’s three-parameter hybrid method utilizing the Lee-Young-Parr correlation functional (B3LYP). After initial energy optimization using Møller-Plesset Perturbation theory (MP2), the conformational preferences and energetics in vacuo were investigated using DFT calculations and the 6-31G(d,p) basis set. Subsequently, cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the compounds in terms of their usefulness as electrolyte additives. At least two of these show excellent promise for use in lithium-ion batteries.

The present thesis deals in detail the influence of solvent dynamics and solvation on ion transport in succinonitrile based plastic crystalline electrolytes. The main objective of correlating plastic solvent characteristics with ion transport was achieved by probing the electrolyte using characterization techniques at various length and time scales. Although majority of the results presented in this thesis focus on a prototype succinonitrile electrolyte (succinonitrile-lithium perchlorate, SN-LiClO4), the conclusions drawn from the results on SN-LiClO4 are quite general and can be extended to various types of salts as well as plastic crystalline matrices. Chapters 2-5 demonstrate in a systematic and detailed manner the beneficial influence of solvent dynamics on ion transport in the solid state. The thesis comprises of six chapters. A brief discussion of the contents and highlights of the individual chapters are described below: Chapter 1 briefly reviews the importance of various types of electrolytes for electrochemical applications. The chapter starts with a discussion on different types of liquid and solid crystalline electrolytes and their drawbacks in electrochemical devices such as lithium-ion batteries. Following the discussion on the two extremes of electrolytes viz. liquid and solid electrolytes, various soft matter electrolytes including polymer and plastic crystalline materials are discussed. Aims of the thesis are specified in chapter 1. Chapter 2 discusses plastic crystalline electrolytes as prospective electrolytes for electrochemical applications. In this chapter, we present a detailed study of correlation of ion transport with solvent structure and dynamics in lithium perchlorate (LiClO4)-succinonitrile (SN), a prototype succinonitrile based plastic crystalline electrolyte. Significant influences of the salt on the crystallographic structure, trans-gauche isomerism and solvation properties of succinonitrile (SN) are observed. Ionic conductivity (ac-impedance spectroscopy) and single crystal X-ray studies (in-situ cryo crystallography) reveal the influence of configurational isomerism and ion solvation on ion transport in LiClO4-SN. We quantify the ion association using theoretical analysis of Fuoss-Onsager formalism for various LiX-SN (typically X = ClO4-, CF3SO3-, TFSI-) electrolytes. Thermal (differential scanning caloriemetry) and spectroscopic (Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR)) studies have also been discussed in the chapter to support our proposition. Chapter 3 describes our investigation on issues other than salt that are likely to affect ion transport in Li-salt-SN based plastic crystalline electrolytes such as water in sample and sample thermal history. We investigate here in a detailed manner the influence of water and thermal history on SN configurational isomerism and solvation in LiClO4-SN. LiClO4 in SN electrolyte samples were prepared in various ways for the fulfillment of the objectives of the study of the present chapter. Correlation of water and thermal history on ion transport were studied via ac-impedance spectroscopy and room temperature Fourier transform infrared (FTIR) spectroscopy. The ionic conductivity and infra-red findings were supplemented via differential scanning calorimetry (DSC). Chapter 4 presents dielectric relaxation spectroscopy (DRS) to study the various relaxation processes of the plastic crystalline solvent and ionic species responsible for ion-transport in succinonitrile-based electrolytes. For the DRS study, we select the same system i.e. SN-LiClO4 for which the role of solvent dynamics and ion-association on ion transport was discussed in detail in chapter 2. We supplement the ionic conductivity and various spectroscopic investigations highlighted in chapter 2 via study of the frequency dependence of dielectric function. The permittivity data are further analyzed using Havriliak-Negami (HN) and Kohlrausch-Williams-Watta (KWW) functions for identification of various processes and also for detailed insight on the ion transport mechanism. Chapter 5 comprises of the temperature dependence the bulk acoustic phonons in SN and SN-LiX (X = ClO4-, CF3SO3-, TFSI-, Cl-) electrolytes from (200-300) K. Room temperature Brillouin spectra of SN based plastic crystalline electrolytes with different cationic salts (MClO4-, M = Li+, Na+, Rb+) were also measured. The influences of salt concentration and temperature on solvent dynamics and ion-association effect have been investigated in detail for the SN-LiClO4 electrolyte. The Brillouin data were further analyzed using Lorentzian and Fano resonance function for identification of behavior of various Brillouin modes. An attempt was made to understand ion transport mechanism in SN-LiX plastic crystalline electrolytes based on the concept of molecular liquids as opposed to conventional solid state defect chemistry. The chapter also discusses preliminary results on the relaxational dynamics of SN and SN-LiClO4 in the plastic phase examined using quasi elastic neutron scattering (QENS) facility at ILL-Grenoble IN16 beamline. Chapter 6 provides a brief summary of the work presented in the thesis and discusses how knowledge from the present work (chapters 2-5) can be utilized to generate new electrolytes. The system proposed is a liquid electrolyte based on bis-nitrile (G0-CN) which does not possess majority of the detrimental issues associate with conventional liquids and various improvisations of polymer electrolytes. We also show that the various dendrimer generations obtained from the monomer bis-nitrile (G0-CN) can also be utilized as an alternative solvent for generation of liquid electrolytes for electrochemical devices such as (primary/secondary) batteries. In a way, we discuss a novel liquid electrolyte system whose physical (viscosity, dielectric constant) and solvation properties can be tuned easily to fulfill task of specific objectives. The preliminary ionic conductivity, viscosity and electrochemical studies of the Gn-CN-Li-salt (n=0-2) liquid electrolytes show considerable promise. Though the prospective dendrimer solvent is a liquid, we envisage that in future compounds with similar chemical properties can also be synthesized in the soft matter state.

Fast ionic conductors, i.e. materials in which charge transport mainly occurs through the motion of ions, are an important class of materials with immense scope for industrial applications. There are different classes of fast ionic conductors e.g. polymer electrolytes, glasses, oxide ion conductors etc. and they find applications such as solid electrolytes in batteries, in fuel cells and in electro active sensors. There are mixed conducting materials as well which have both ions and electrons as conducting species that are used as electrode materials. Specifically, polymer electrolytes 1−3 have been in use in lithium polymer batteries, which have much more advantages compared to other secondary batteries. Polymer electrolyte membranes have been in use in direct methanol fuel cells (DMFC). The membranes act as proton conductors and allow the protons produced from the fuel (methanol) to pass through. Oxide ion conductors are used in high temperature solid oxide fuel cells (SOFC) and they conduct via oxygen ion vacancies. Fuel cells are rapidly replacing the internal combustion engines, because they are more energy efficient and environment friendly. The present thesis is concerned with the preparation, characterization and conductivity studies on the following fast ionic conductors: (MPEG)xLiClO4, (MPEG)xLiCF3SO3 where (MPEG) is methoxy poly(ethylene glycol), the hydrotalcite [Mg0.66Al0.33(OH)2][(CO3)0.17.mH2O] and the nanocomposite SPE, (PEG)46 LiClO4 with dispersed nanoparticles of hydrotalcite. We also present our investigations of spin probe electron spin resonance (SPESR) as a possible technique to determine the glass transition temperature (Tg) of polymer electrolytes where the conventional technique of Tg determination, namely, differential scanning calorimetry, (DSC), is not useful due to the high crystallinity of the polymers. In the following we summarize the main contents of the thesis. In Chapter 1 we provide a brief introduction to the phenomenon of fast ionic conduction. A description of the different experimental techniques used as well as the relevant theories is also given in this chapter. In most solid polymer electrolytes (SPE), the usability is limited by the low value of the ionic conductivity. A number of different routes to enhance the electrical, thermal and mechanical properties of these materials is presently under investigation. One such route to enhance the ionic conductivity in polymer electrolytes is by irradiating the polymer electrolyte with gamma rays, electron beam, ion beams etc. In Chapter 2, we describe our work on the effect of electron beam (e-beam) irradiation on the solid polymer electrolytes (MPEG)xLiClO4 and (MPEG)xLiCF3SO3. The polymer used is methoxy poly(ethylene glycol) or poly(ethylene glycol) methyl ether with a molecular weight 2000. Salts used are LiClO4 and LiCF3SO3. ’x’ in the subscript is a measure of the salt concentration; it is the ratio of the number of ether oxygens in the polymer chain to that of the Li+ ion. ’x’ values chosen are 100, 46, 30 and 16. Nearly one order of magnitude increase in the conductivity is observed for samples (MPEG)100LiClO4 and (MPEG)16LiCF3SO3 on irradiation. It was found that the increase in the net ionic conductivity is a function of both the irradiation dose and the salt concentration. The enhanced ionic conductivity remains constant for ∼ 100 hrs, which signifies a possible near permanent change in the polymer electrolyte system due to irradiation. The samples were also characterized using DSC and Fourier transform infrared spectroscopy (FTIR). DSC results could be correlated with conductivity findings, giving low Tg values for samples having high conductivity. It was also found that there is a small increase in the crystalline fraction of the samples on irradiation, which agrees with earlier reports on samples irradiated with low dosage. FTIR results are suggestive of decreased cross linking as the reason for increased ionic conductivity. However, this aspect needs a further confirmatory look before the findings can be termed conclusive. In Chapter 3, we describe the studies we have carried out on Li -doped hydrotalcite. We report the details of preparation and characterization of hydrotalcite as well as NMR and ionic conductivity measurements on both doped (with Li+ ions) and undoped hydrotalcite. Hydrotalcite was prepared by co-precipitation method and the composition of hydrotalcite was chosen as [Mg0.66Al0.33(OH)2][(CO3)0.17.mH2O]. Samples were prepared with salt (LiClO4) concentration 5 %, 10 %, 15 %, 20 % and 25 %. It was found that the highest ionic conductivity occurs for the sample with 20 % doping. 7Li NMR plots for all the samples clearly show an overlap of a Gaussian and a Lorentzian lineshape. The Gaussian line is because of the presence of a less mobile fraction of the 7Li+ ions and the Lorentzian line is because of the presence of a more mobile fraction of 7Li+ ions. The highest ionic conductivity was found for the salt concentration 20 % and from the room temperature 7Li NMR studies we found that for this particular concentration, the mobile fraction of the 7Li ion is also maximum. Without the salt doping, the conductivity of the sample was too small to be measured. Temperature variation of both 1H and 7Li NMR was also done, to compare the ionic conductivities from NMR. Another method to obtain enhanced properties in polymer electrolytes is by forming ’nanocomposite’ polymer electrolytes. Nanocomposites are formed by dispersing nanoparticles of certain materials in the polymer electrolyte matrix. Till now, nanoparticles used are mostly oxides of metals, e.g. Al2O3, TiO2, MgO, SiO2 etc and clays like montmorillonite, liponite, hydrotalcite etc. Chapter 4 describes the preparation and characterization of the nanocomposite polymer electrolyte (PEG)46LiClO4 formed with hydrotalcite nanoparticles. The polymer used is PEG, poly(ethylene glycol) of molecular weight 2000, and salt used is LiClO4. The salt concentration is selected so as to give the highest ionic conductivity for the solid polymer electrolyte. Hydrotalcite belongs to a class of materials called LDH, layered double hydroxides. The composition selected is [Mg0.66Al0.33(OH)2][(CO3)0.17 .mH2O], since this is the most stable composition. These materials are easy to prepare in the nano size and are being used in a number of applications. These are characterized by the presence of layers of positively charged double hydroxides separated by layers of anions and water molecules. The water molecules give stability to the structure. Nanoparticles of hydrotalcite were prepared in the laboratory itself. XRD data of hydrotalcite confirm the crystal structure. TEM data show the particle size to be ∼ 50 nm. The polymer electrolyte (PEG)46LiClO4 was doped with these nanoparticles and the doping levels are 1.8 %, 2.1 %, 2.7 %, 3.6 % and 4.5 % by weight. Impedance spectroscopy was used to find the ionic conductivity. We have found that the sample with a doping of 3.6 % by weight gives the highest ionic conductivity and the increase in ionic conductivity is nearly one order of magnitude. DSC was used for thermal characterization of these nanocomposites. The glass transition temperatures, Tg , found from DSC measurements corroborates the ionic conductivity data, giving the lowest Tg for the sample with highest conductivity. Temperature variation of the ionic conductivity shows Arrhenius behavior. 7Li NMR was done on the pristine SPE (PEG)46LiClO4 and the nanocomposite of (PEG)46LiClO4 with 3.6 % filler. The ionic conductivity was also estimated from the temperature variation of 7Li NMR line widths. Studies on the DSC endotherms of the nanocomposites give the fractional crystallinity of the samples. From these studies it can be concluded that the variation in ionic conductivity can be attributed to the change in fractional crystallinity; the nanocomposite polymer electrolyte having highest ionic conductivity, i.e. the NCPE with filler concentration of 3.6 % also has the lowest fractional crystallinity. Additionally, a possible increase in the segmental motion inferred from a reduction in the glass transition temperature coupled with a lowering of the activation energy may also contribute to the increased ionic conductivity in the nanocomposite polymer electrolyte. Glass transition temperature Tg has a very important role in studying the dynamics of polymer electrolytes. In Chapter 5, we explore the possibility of using spin probe electron spin resonance (SPESR) as a tool to study the glass transition temperature of polymer electrolytes. When the temperature of the polymer is increased across the glass transition, the viscosity of the sample decreases. This corresponds to a transition from a slow tumbling regime with τc = 10−6 s to a fast tumbling regime with τc = 10−9 s where τc is the correlation time for the probe dynamics. Spin probe ESR can be used to probe this transition in polymers. We have used 4-hydroxy tempo (TEMPOL) as the spin probe which is dispersed in the nanocomposite polymer electrolyte based on (PEG)46LiClO4 and hydrotalcite. Below and across the glass transition, this nitroxide probe exhibits a powder pattern showing both Zeeman (g) and hyperfine (hf) interaction anisotropy. When the frequency of the dynamics increases such that the jump frequency f is of the same order of magnitude as the anisotropy of the hf interaction, i.e., ∼ 108 Hz, the anisotropy of the interactions averages out and a spectrum of reduced splitting and increased symmetry in the line shape is observed. This splitting corresponds to the nonvanishing isotropic value of the hyperfine tensor and is observed at a temperature higher than but correlated with Tg. The crossover from the anisotropic to isotropic spectrum is reflected in a sharp reduction in the separation between the two outermost components of the ESR spectrum, which corresponds to twice the value of the z-principal component of the nitrogen hyperfine tensor, 2Azz, from ∼75 G to ∼ 35 G. In our study, we have varied the concentration of the nano-fillers. The Tg for all the samples were estimated from the measurement of T50G and the known correlation between 4 T50G and Tg, where T50G is the temperature at which the extrema separation (2Azz) of the ESR spectra becomes 50 Gauss. The values obtained from this method are compared with the values found from DSC done on the same samples. Within experimental error, these two techniques give reasonably close values. Tg’s were also estimated by a cross over in the correlation time (τc) vs temperature plot. The τc values were calculated using a spectral simulation program. We conclude that spin probe ESR can be an alternative to the DSC technique for polymers with high fraction of crystallinity, for which DSC often does not give any glass transition signature. In Appendix I, ionic conductivity studies on quenched and gamma irradiated polymer electrolytes (PEG)46LiClO4 and (MPEG)16LiClO4 is done. It is observed that, (i) the samples quenched to 77 K after melting show enhancement of ionic conductivity by a factor of 3 & 4; (ii) on irradiation, the ionic conductivity decreases for a dose of 5 kGy and subsequently, keeps on increasing for higher doses of 10 kGy and 15 kGy. In Appendix II, the BASIC language program (eq-res.bas) used for impedance data analysis is given.

Les ionomères aromatiques sont considérés comme une alternative prometteuse à Nafion pour les PEMFCs en raison de leur bonne stabilité à l'oxydation, d'excellentes propriétés thermomécaniques et de faibles coûts, etc. La plupart des ionomères aromatiques sulfonés rapportés au cours des dernières décennies présentent cependant des performances inférieures à celles de Nafion. Avec une capacité d'échange ionique (CEI) similaire, d'une part, les ionomères aromatiques sont beaucoup moins conducteurs que Nafion, notamment à faible humidité relative. Les ionomères aromatiques ayant une CEI suffisante pour donner une conductivité équivalente à celle de Nafion, d'autre part, présentent un comportement excessivement gonflant dans l'eau. Les inconvénients des ionomères aromatiques sulfonés proviennent de (i) la répartition aléatoire de groupes acides sur un squelette de polymère rigide conduisant à une séparation hydrophile-hydrophobe faible, (ii) la proximité de fractions conductrices de protons à la chaîne principale de polymère conduisant à une nanostructure basse de composés ioniques, et (iii) la faible acidité de l'acide arylsulfonique. Dans le but de surmonter ces inconvénients, mon travail de doctorat se concentre sur le développement de nouveaux ionomères aromatiques avec une morphologie et des propriétés améliorées grâce à la conception de l'architecture moléculaire, en combinaison avec une condition optimisée de traitement de la membrane. A base de cet objectif, deux séries d'ionomères aromatiques à base de copoly (arylène éther sulfone) partiellement fluoré portant des chaînes latérales pendantes d'acide perfluorosulfonique (séries InX/Y) ou perfluorosulfonimide (SiX/Y) ont été développées et caractérisées. De plus, les PEM basés sur le mélange Nafion/InX/Y ont également été ciblés. Une grande attention a été portée à l'optimisation de l'état de traitement des membranes et à l'élucidation de la relation structure-morphologie-propriété des matériaux. / Aromatic ionomers are considered as a promising alternative to Nafion for PEMFCs due to their good oxidative stability, excellent thermomechanical properties, and low cost, etc. Most sulfonated aromatic ionomers reported over the past decades, however, show lower performance than that of Nafion. With similar ion-exchange capacity (IEC), on one hand, aromatic ionomers are much less conductive than Nafion, notably at low relative humidity. Aromatic ionomers with sufficient IEC to give equivalent conduction to that of Nafion, on the other hand, exhibit excessively swelling behavior in water. The shortcomings of sulfonated aromatic ionomers derive from (i) the random distribution of acidic groups on rigid polymer backbone leading to poor hydrophilic-hydrophobic separation, (ii) the proximity of proton-conducting moieties to the polymer main chain resulting in low nanostructure of ionic clusters, and (iii) the low acidity of aryl sulfonic acid. With the aim of overcoming these drawbacks, my PhD work focuses on developing new aromatic ionomers with improved morphology and properties via molecular architecture design, in combination with optimized membrane processing condition. Based on this objective, two series of aromatic ionomers based on partially-fluorinated multi-block copoly(arylene ether sulfone)s bearing pendant perfluorosulfonic acid (InX/Y series) or perfluorosulfonimide (SiX/Y series) side chains have been developed and characterized. Moreover, PEMs based on Nafion/InX/Y blend have also been focused. Much attention has been paid to optimizing the membrane processing condition and elucidating the structure-morphology-property relation in these materials.

No description available.

<p>The Materials Genome Initiative (MGI) has established guidelines to accelerate the discovery, development, and implementation of advanced materials in order to address current and future challenges. A key area of interest is the pressing need for more efficient energy storage systems to support technologies such as electric vehicles and renewable energies. In this work, we present an Integrated Computational Materials Engineering approach for the development of novel solid-state electrolyte materials. In particular, we embark on a quest to unravel the potential of ceramic garnet lithium lanthanum zirconium oxide (LLZO) for next-generation battery technologies.</p> <p>Our exploration begins with an overview of the current state of the Materials Innovation Infrastructure (MII) and our rationale behind choosing LLZO. Through the use of machine learning techniques and molecular dynamics simulations, we aim for efficient material optimization. Our findings are reinforced through experiments by using these materials as inorganic fillers in composite polymer electrolytes. Our findings demonstrate that the combined use of these complementary techniques facilitates the discovery of potential alternative solid-state electrolytes. Finally, we propose future research directions in materials science for the design of advanced materials using these integrated approaches. </p>