Letteratura scientifica selezionata sul tema "Multivalent-Ion"

ABSTRACTThe need for higher energy density batteries has spawned recent renewed interest in alternatives to lithium ion batteries, including multivalent chemistries that theoretically can provide twice the volumetric capacity if two electrons can be transferred per intercalating ion. Initial investigations of these chemistries have been limited to date by the lack of understanding of the compatibility between intercalation electrode materials, electrolytes, and current collectors. This work describes the utilization of hybrid cells to evaluate multivalent cathodes, consisting of high surface area carbon anodes and multivalent nonaqueous electrolytes that are compatible with oxide intercalation electrodes. In particular, electrolyte and current collector compatibility was investigated, and it was found that the carbon and active material play an important role in determining the compatibility of PF6-based multivalent electrolytes with carbon-based current collectors. Through the exploration of electrolytes that are compatible with the cathode, new cell chemistries and configurations can be developed, including a magnesium-ion battery with two intercalation host electrodes, which may expand the known Mg-based systems beyond the present state of the art sulfide-based cathodes with organohalide-magnesium based electrolytes.

Multivalent batteries are an energy storage technology with the potential to surpass lithium-ion batteries, however their performance has been limited by the low voltages and poor solid-state ionic mobility of available cathodes. A computational screening approach to identify high-performance multivalent intercalation cathodes among materials that do not contain the working ion of interest has been developed which greatly expands the search space that can be considered for materials discovery. This approach has been applied to magnesium cathodes as a proof of concept and resulting candidate materials are discussed in further detail. In examining the ion migration environment and associated Mg2+ migration energy in these materials, local energy maxima are found to correspond with pathway positions where Mg2+ passes through a plane of anion atoms. While previous works have established the influence of local coordination on multivalent ion mobility, these results suggest that considering both the type of local bonding environment as well as available free volume for the mobile ion along its migration pathway can be significant for improving solid-state mobility.

As lithium-ion batteries (LIB) start to approach their theoretical limit, researchers are focusing on alternatives such as nonaqueous multivalent systems. There are many advantages of multivalent systems such as higher natural abundance, low cost and possible high volumetric capacity. Suitable electrolytes are vital for the development of such multivalent battery systems which offer compatibility of utilizing metal anode. To create a better understanding of the opportunities and challenges of the trivalent electrolytes in aluminum batteries, this work investigates the reaction mechanisms and SEI interactions at the electrolyte/electrode interface.

This dissertation focuses on the synthesis and electrochemical testing of new electrolyte salts for rechargeable multivalent ion batteries. In chapters 2 and 3 the synthesis of Mg and Ca hexafluoropnictogenate salts as well as the electrochemical behaviour of Mg(PF6)2 is presented. Pure samples of Mg(EF6)2 (E = P, As, and Sb) can be synthesized using Mg metal and NOPF6/NOSbF6 in CH3CN or via a ammonium salt deprotonation route using Me3NHAsF6 and Bu2Mg. The NOPF6 method was extended to the Ca variant, but isolation of a pure Ca(PF6)2 material required the presence of a crown ether. Electrochemical and microscopy measurements of THF-CH3CN solutions of Mg(PF6)2 show that the electrolyte good electrochemical stability and can facilitate the plating/stripping of Mg. Further, this electrolyte system can be cycled in a full cell using the Chevrel phase Mo6S8 cathode. The electrochemical stability of the AsF6− and SbF6− salts is lower than that of the PF6− salt and electrolyte decomposition is observed when cycling on Mg electrodes. In chapter 4 the development of a series of Mg aluminates [Mg(AlOR4)2] using a general synthetic platform based on Mg(AlH4)2 and various alcohols is presented. Preliminary electrochemical studies performed on these aluminate salts in dimethoxyethane identify the phenoxy and perfluoro-tert-butoxy derivatives as promising electrolyte systems. Electrochemical cycling of these electrolytes using gold and Mg electrodes show that systems containing chloride, brought through to the product from the starting material in the form of NaCl, exhibit lower plating/stripping overpotentials and higher Coulombic efficiencies than systems from which chloride had been removed. Further, these two electrolytes can be used in Mg full cells containing the Chevrel phase cathode. Solid-state 23Na NMR analysis as well as DFT calculations show that chloride-containing electrolytes facilitate the co-insertion of Na into the cathode material. In chapter 5 the hydroboration of pyridines and CO2 in the presence of pinacolborane is presented. An optimized system employing NH4BPh4 and HBpin is developed and a mechanism of pyridine hydroboration is proposed based on multinuclear NMR spectroscopy. The catalytic reaction was found to be catalyzed by a boronium salt, which was structurally characterized in the solid-state by single crystal X-ray diffraction. This new catalytic method is shown to be tolerant to a number of functional groups in the 3-position on pyridine as well as quinoline, and CO2, producing the hydroboration products in good yields.

Le premier chapitre introduit le concept et les caractéristiques fondamentales des matériaux moléculaires. Il met en évidence leurs vastes applications et les avantages qu'ils offrent dans les dispositifs électrochimiques, ainsi qu'un aperçu de leur développement dans ce domaine. Ensuite, les matériaux moléculaires sont classés de trois manières distinctes selon différents critères. Les sous-catégories de chaque classification sont systématiquement expliquées, mettant en lumière différents aspects des matériaux moléculaires selon la méthode de classification.À partir des batteries à ions multivalents, le deuxième chapitre introduit la batterie à ions aluminium émergente comme un système de stockage avec un grand potentiel. Les avantages du développement des batteries à ions aluminium sont montrés à partir des avantages objectifs de l'abondance naturelle et du prix de l'aluminium lui-même, ainsi que du potentiel électrochimique théorique de l'aluminium. Ensuite, du point de vue des électrolytes et des matériaux d'électrode, les batteries à ions aluminium et leur état de développement sont résumés à travers une classification détaillée et des exemples.Par conséquent, sur la base de notre compréhension des matériaux moléculaires et des batteries à ions aluminium, nous avons mené les deux projets suivants :Dans un travail de pionnier, nous avons rapporté les capacités de stockage d'ions lithium du polymère de coordination unidimensionnel (1D) bimétallique fer-nickel, {[FeIII(Tp)(CN)3]2[NiII(H2O)2]}n. Le résultat a d'abord confirmé l'intercalation réversible de Li+ dans le matériau moléculaire à pont cyanure 1D. Cette tentative réussie dans les batteries à ions lithium a éveillé notre intérêt pour explorer davantage la possible insertion d'ions aluminium dans une telle chaîne à pont cyanure unidimensionnelle. Dans ce travail, nous avons sélectionné l'électrolyte liquide ionique ([EMIm]Cl-AlCl3 avec un rapport de 1,1:1 (AlCl3 : ([EMIm]Cl)) comme électrolyte, et développé une série de matériaux unidimensionnels (1D) avec la formule {[FeIII(Tp)(CN)3]2[MII(H2O)2]}n (M = Ni, Co, Mn, Zn, Cu). Nous avons supposé que la faible dimensionnalité et la structure ouverte de ces composés pourraient permettre une (dés)intercalation ionique plus facile et une meilleure capacité d'accueil des ions Al. Nous pouvons également émettre l'hypothèse que la présence d'une enveloppe organique (ligands Tp) dans les chaînes pourrait favoriser des interactions électrostatiques plus faibles entre le cation multivalent inséré et le cadre, et donc une meilleure diffusion. De plus, des comparaisons entre les composés pontés par différents métaux divalents, y compris le zinc inactif, sont destinées à aider à comprendre les effets multiples des métaux pontés sur les composés.Ensuite, nous avons abordé le deuxième sujet basé sur l'acide chloranilique. Il s'agit d'une série de cadres bidimensionnels (2D), car nous souhaitons tirer parti de la haute stabilité de la structure 2D et compter sur les groupes carbonyles potentiels pour réaliser l'intercalation et la désintercalation. En conséquence, les tests préliminaires prouvent la stabilité de cette série de cadres. Étant donné qu'il s'agit d'un projet en cours et que nous n'avons rapporté que les données jusqu'à présent, une investigation plus approfondie de cette série est nécessaire
The first chapter introduces the concept and fundamental characteristics of molecular materials. It highlights their broad applications and the advantages they offer in electrochemical devices, along with an overview of their development in this field. Then, molecular materials are classified in three distinct ways based on different criteria. Each classification's subcategories are systematically explained, highlighting different aspects of molecular materials according to the classification method.Starting from multivalent ion batteries, the second chapter introduces the emerging aluminum ion battery as a storage system with great potential. The advantages of developing aluminum ion batteries are shown from the objective advantages of the natural abundance and price of aluminum itself, and the theoretical electrochemical potential of aluminum. Then, from the two aspects of electrolyte and electrode materials, aluminum ion batteries and their development status are summarized through detailed classification and examples.Therefore, based on our understanding of molecular materials and aluminum ion batteries, we conducted the following two projects:In a seminal work, we reported the lithium-ion storage capabilities of the iron-nickel bimetallic one-dimensional (1D) coordination polymer, {[FeIII(Tp)(CN)3]2[NiII(H2O)2]}n. The result first confirmed the reversible Li+ (de)intercalation in the 1D cyanide-bridged molecular material. This successful attempt in lithium-ion batteries aroused our interest in further exploring the possible insertion of aluminium ions into such one-dimensional cyano-bridge. In this work, we selected ([EMIm]Cl-AlCl3 ionic liquid with the ratio of 1.1:1(AlCl3 : ([EMIm]Cl) as electrolyte, and developed a series of one-dimensional (1D) material with the formula{[FeIII(Tp)(CN)3]2[MII(H2O)2]}n (M=Ni, Co, Mn, Zn, Cu). We expected the lower dimensionality and open framework of these compounds could permit easier ion (de)intercalation and a better Al-ion host capability. We can also hypothesize that the presence of organic shell (Tp ligands) in the chains could favor weaker electrostatic interactions between the inserted multivalent cation and the framework, and thus a better diffusion. Furthermore, comparisons between compounds bridged different divalent metals, including inactive zinc, are intended to help understand the multifaceted effects of bridged metals on compounds.Then, we conducted the second topic based on chloranilic acid. It is a series of 2D frameworks, as we would like to take advantage of the high stability of 2D structure and rely on the potential carbonyl groups to realize the intercalation and deintercation. As a result, the preliminary tests prove the stability of this series of frameworks. Since this is an ongoing project and we have only reported the data so far, further investigation of this series is needed

La vinasse de distillerie, co-produit de l’industrie canne-sucre-alcool-énergie, contient de 5 à 7 g/L d’un acide d’intérêt, l’acide aconitique, au sein d’un milieu complexe comportant d’autres acides organiques, des acides aminés, mais surtout des sels minéraux (chlorures et sulfates) et des colorants, rendant sa purification complexe. Afin d’améliorer les performances du procédé d’échange d’ions, au coeur de cette purification, la résine anionique faible Lewatit S4528 a été caractérisée. Le dosage de la résine et des mesures d’isothermes d’échange d’ions ont permis de définir : la capacité totale du support, l’ordre d’affinité des principaux anions de la vinasse et les coefficients d’échange d’ions associés, de même que la capacité pour l’acide d’intérêt dans cette matrice complexe. L’effet du pH, de la forme du support (sulfate, chlorure et base libre) et de l’éluant ont été étudiés en colonne pour différentes solutions (acide seul, vinasse « modèle », vinasse réelle), permettant de préciser les mécanismes de la purification.Les meilleures conditions (vinasse à pH 4,5, résine sous forme chlorure et élution par HCl 0,5 N) ont abouti à un éluat d’une pureté de 28 %MS avec un rendement global de 61 %. Pour éliminer les principales impuretés qui persistent dans l’éluat (ions chlorure et sulfate et des colorants), l’électrodialyse s’est avérée un procédé très performant en ce qui concerne l’élimination des ions chlorure (proche de 100 %) tandis qu’une étape d’adsorption sur résine polystyrénique XAD16 permet l’élimination de 80 % de la charge colorante de l’éluat acide. Le couplage le plus intéressant associe microfiltration, échange d’ions, électrodialyse et adsorption. Il permet d’obtenir une pureté estimée à 37 % MS, avec un facteur de purification de 3,6 par rapport à la vinasse initiale. Ces travaux ont permis d’améliorer d’un facteur 2,6 la pureté de l’acide par rapport à des études antérieures et de mieux comprendre les mécanismes de sa purification sur résine anionique faible
Cane stillage or vinasse, a byproduct of cane industry, contains from 5 to 7 g/L of aconitic acid, a valuable trivalent carboxylic acid belonging to the second class of building block chemicals. Vinasse also contains a variety of organic compounds (organic acids, amino-acids, colouring matters) and minerals (chlorides, sulphates), which makes purification not straightforward. The objective of this work is to develop the extraction of aconitic acid from stillage, with anion exchange as the heart of the process. In order to improve performances, the main characteristics of the selected anion-exchange resin (Lewatit S4528) are studied. Acid-base dosage and ion-exchange equilibrium experiments allow the total capacity of this support and the ion-exchange coefficients for the major competing anions (aconitate, chloride and sulfate) to be obtained. Separation performances in column are studied for different pH, different solutions (aconitic acid alone, synthetic and industrial stillage) and different resin forms (sulfate, chloride and free- base) in order to elucidate the separation mechanisms.Elution step is also investigated. Best conditions are for stillage at its natural pH (pH 4.5) on the resin under chloride form and HCl 0,5N as the eluant. A 28% DM purity and a 61% global recovery are achieved for aconitic acid in the eluate. Main impurities still remaining are chlorides or sulfates and coloring matter. Homopolar electrodialysis proves successful for removing nearly 100% chlorides from aconitic acid with a limited loss of the acid (< 15%). Adsorption step on a polystyrenic resin (XAD16) of an acidic eluate leads to the retention of 80% of the colorants, with only 12% of the acid lost. At last, the most interesting process combination associates microfiltration, anion-exchange, electrodialysis and adsorption. Purity is 37% MS, namely 3.6 higher than the original vinasse. This work enables aconitic acid purity to be improved by a factor of 2.6 compared with prior studies and to have a better comprehension of the mechanisms involved in its purification on weak anionic resin

Alginate is a natural polymer that can form complexes in the presence of multivalent metal. In this chapter, we summarized the newest alginate metal complexes application in many fields; organic synthesis, environmental and medical application. The main idea was about alginate complexes’ role in the drug delivery system as a chiral excipient to reach the enantioselective release in the case of chiral drugs. We also present a case study about the ketoprofen enantioselective release investigation from alginate mixed beads with two ion metal types.

On a liquid metal electrode all surface sites are equivalent, and the deposition of a metal ion from the solution is conceptually simple: The ion loses a part of its solvation sheath, is transferred to the metal surface, and is discharged simultaneously; after a slight rearrangement of the surface atoms it is incorporated into the electrode. The details of the process are little understood, but it seems that the discharge step is generally rate determining, and the Butler-Volmer equation is obeyed if the concentration of the supporting electrolyte is sufficiently high. For example, the formation of lithium and sodium amalgams [1] in nonaqueous solvents according to: . . .Li + + e- ⇌ Li(Hg) Na+ = e- ⇌ Cd(Hg) . . . (10.1) obey the Butler-Volrner equation with transfer coefficients that depend on the solvent. On the other hand, the deposition of multivalent ions may involve several steps. Thus, the formation of zinc amalgam from aqueous solutions, with the overall reaction: . . . zn2+ + 2e- ⇌ Zn (Hg) . . . (10.2) occurs in two steps: First, Zn2+ is reduced to an intermediate Zn+ in an electron transfer step, and then the univalent ion is deposited [2]. In contrast, the surface of a solid metal offers various sites for metal deposition. Figure 10.1 shows a schematic diagram for a crystal surface with a quadratic lattice structure. A single atom sitting on a flat surface plane is denoted as an adatom; several such atoms can form an adatom cluster. A vacancy is formed by a single missing atom; several vacancies can be grouped to vacancy clusters. Steps are particularly important for crystal growth, with kink atoms, or atoms in the halfcrystal position, playing a special role. When a metal is deposited onto such a surface, the vacancies are soon filled. However, the addition of an atom in the kink position creates a new kink site; so at least on an infinite plane the number of kink sites does not change, and the current is maintained by incorporation into these sites. Similarly metal dissolution takes place predominantly at half-crystal positions, since the removal of a kink atom creates a new kink site.

Interaction between solid surfaces in aqueous electrolyte solutions is of great importance to many diverse domains, such as bioMEMS, nanofluidics, colloid science, polymer physics, and molecular biophysics. Several counterintuitive phenomena occur at high concentrations of multivalent ions. In this article, charge reversion, the sign reversal of the effective surface charge in the presence of multivalent counterions, is directly observed through the force between two mica surfaces in aqueous solutions of trivalent cations by surface forces measurements. The effective surface potential functioned with bulk concentration is calculated from an analytical model based on ion correlations. The obtained force profiles can be described by the analytical model when ion correlations effects are taken into account, while Poisson-Boltzmann theory fails. It reveals that ion correlations are important for screening charged surface in the presence of multivalent counterions.

Multivalent rare earth ion, Sm+2/Sm+3 was incorporated into aluminosilicate glass fiber using an aerosol delivery technique. Co-doping of trivalent and divalent states of the ions has been spectroscopically confirmed. Irradiated by multi-line CW Ar ion laser of 1 Watt, the fiber showed photoinduced refractive change of 7.6 × 10−5. Bleaching of Sm+2 absorption band was also observed. Photoionization of Sm+2 is believed to be a main cause of the photosensitivity.

Abstract Low-salinity waterflooding is a relatively simple and cheap improved oil recovery technique in which the reservoir salinity is optimized to increase oil recovery. Multivalent ion enriched as well as diluted brines have shown promising potential to increase oil production over conventional waterflooding. While the literature generally acknowledges that low-salinity improves oil recovery, the physical mechanisms behind low-salinity effects are still controversial. Surface charge change refers to a low-salinity mechanism in which modified brine is believed to cause a re-equilibrium of the carbonate surface potential. As a result of surface charge change, the rock wettability alters towards a more water-wetting state. This experimental study combines zeta potential, spontaneous imbibition, and contact angle measurements to highlight the effect of carbonate minerals on surface charge change. Initially, zeta potential measurements were conducted to compare the impact of five carbonate minerals (Indiana Limestone, Edward Limestone, Reservoir Limestone, Austin Chalk, and Silurian Dolomite) and brine compositions (Formation-water, Sea-water, and Diluted-sea-water) on carbonate surface charge. Moreover, the impact of potential determining ions (calcium, magnesium, and sulfate) on the mineral surface charge was investigated. The effect of carbonate minerals on spontaneous oil recovery was investigated by comparing the spontaneous imbibition of Formation-water, Sea-water, and Diluted-sea-water into the five carbonate minerals. Moreover, the wettability alteration during the spontaneous imbibition tests was quantified by conducting contact angle measurements. The brine-mineral zeta potential measurements were positive for Formation-water, slightly negative for Sea-water, and strongly negative for Diluted-sea-water. While calcium and magnesium ions promoted stronger positive electrical potentials, sulfate ions caused a zeta potential reduction. The magnitude of surface charge change was significantly different for the five tested carbonate minerals. Under the presence of Diluted-sea-water, the zeta potential measurements of Indiana Limestone and Austin Chalk resulted in strong negative electrical potentials. Reservoir Limestone and Edward Limestone showed less negative zeta potentials, while Silurian Dolomite and Diluted-sea-water resulted in slightly negative zeta potential results. Compared to Formation-water, Sea-water, and particularly Diluted-sea-water caused significant spontaneous oil recovery. The high spontaneous oil recovery of Diluted-sea-water and Indiana Limestone and Austin Chalk correlated with strong negative brine-mineral zeta potentials. Moderate spontaneous oil recovery was observed for the slightly negative zeta potential Sea-water and limestone/chalks systems. The contact angle measurements showed oil-wet contact angles under the presence of Formation-water, while the introduction of Sea-water and Diluted-sea-water promoted stronger water-wet contact angles. This work is one of the very few studies that investigates the effect of carbonate rock mineralogy on surface charge change and spontaneous oil recovery.