Mixture Of LiCl Research Articles

Electrochemical, gravimetric and surface studies of Phalaris canariensis oil extract as corrosion inhibitor for 316 L type stainless steel in H2O-LiCl mixtures

The corrosion inhibition action of Phalaris canariensis extract on 316 L stainless steel in the H2O-35 (wt%) LiCl mixture at different temperatures has been evaluated with the aid of weight loss, potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy tests. These studies were complemented by Fourier Transformed Infrared spectroscopy, FTIR, gas/mass chromatography analytical techniques and detailed scanning electronic microscopy studies. Results have indicated that Phalaris canariensis extract is an efficient inhibitor, with an efficiency that increases with its concentration, but it decreases as the temperature increases. Phalaris canariensis extract is physically adsorbed onto stainless steel according to a Temkin type of adsorption isotherm. Phalaris canariensis extract affected both anodic and cathodic electrochemical reactions with a stronger effect on the anodic ones, acting, thus, as a mixed type of inhibitor. Main compounds contained in the Phalaris canariensis extract were palmitic and oleic acids, responsible for its inhibitory properties.

Highly efficient recovery of lithium from spent ternary NCM cathode materials via a selective chlorination method

The recovery of lithium from spent lithium-ion batteries (LIBs) is an important approach to solve the global shortage of lithium resource. Considering the difference in stability of various metal element chlorides in Ni-Co-Mn ternary (NCM) cathode materials, lithium element was selectively and high-efficiently extracted from spent ternary NCM cathode material by ammonium chloride roasting in oxygen atmosphere followed by water leaching. The effects of roasting temperature, roasting time, and NH4Cl dosage on lithium leaching efficiency and selectivity were systematically investigated. In addition, the conversion mechanism during chloride roasting was discussed in detail in conjunction with thermodynamic analysis as well as structural and compositional characterizations. After roasting with NH4Cl in oxygen atmosphere at 600°C, the spent NCM cathode material was thoroughly decomposed and converted into mixture of LiCl, NiO, and MnCo2O4. Due to the high aqueous solubility of LiCl, more than 95 % of the lithium in the mixture was leached in ∼30 minutes at room temperature, and Li2CO3 with a purity of 99.40 % can be obtained in the subsequent recovery process. This simple and efficient method can be generally useful for the recovery of a wide range of spent cathode materials and provide inspiration for the lithium recovery process of spent LIBs.

Highly selective Mg2+/Li+ separation membranes prepared by surface grafting of a novel quaternary ammonium bromide

The efficient separation of Mg2+ and Li+ is the crucial step in the process of extracting lithium from salt lake brine. Nanofiltration (NF) membranes exhibit promising application potential in Mg2+/Li+ separation but the Mg2+/Li+ selectively of negatively charged NF membranes prepared by conventional interfacial polymerization process is far from desirable. In this study, a novel positively charged quaternary ammonium bromide, 3-bromopropyl trimethylammonium bromide (BTAB), is grafted on the polyethyleneimine (PEI)/trimesoyl chloride (TMC) NF membrane surface. This is achieved by a chemical reaction known as nucleophilic substitution, which involves the replacement of a bromine atom (-Br) with an amine group. Owing to the enhanced Donnan effects, the BTAB-modified NF membranes exhibit a MgCl2 rejection of up to 99.2 %, while maintaining a water flux of approximately 50 LMH under 5 bar. Meanwhile, the LiCl rejection is only ∼ 30 %. The Mg2+/Li+ selectively of the BTAB-modified NF membranes reaches 95.9 when filtrating a simulated brine with a Mg2+/Li+ ratio of 20 (2000 ppm MgCl2 and LiCl mixture), which is a twofold improvement compared with the pristine NF membranes. The working stability of the BTAB-modified NF membranes is confirmed by a 50-h continuous operation process. A two-stage NF treatment is conducted using a simulated East Taijinar salt lake brine, achieving Li2CO3 powder with a purity level of 99.4 %. The nucleophilic substitution reaction between -Br and the amine groups offers a good reference for the surface functionalization of NF membranes.

Positively charged nanofiltration membranes for efficient Mg2+/Li+ separation from high Mg2+/Li+ ratio brine

Nanofiltration has gained increasing attention in lithium extraction from salt lake brine with high Mg2+/Li+ ratio. However, conventional nanofiltration membranes with negatively charged surfaces suffer from low Mg2+/Li+ selectivity. Herein, positive nanofiltration membranes with high charge density were fabricated via a two-step charge enhancement strategy. High concentration of polyethylenimine was used as the aqueous monomer to ensure the abundant amino groups on the membrane surface. To further enhance the electro-positivity, 2, 3-epoxypropyl trimethyl ammonium chloride was grafted through ring-opening reactions. The as-obtained membranes demonstrated positive zeta potentials over a large pH range (3-10), leading to significantly strengthened Donnan exclusion for Mg2+. The membrane rejection to MgCl2 was up to 99.3% while the rejection to LiCl was only ∼30%. The Mg2+/Li ​+ ​separation factor was 167 when filtration simulated brine with a Mg2+/Li+ ratio of 20 (2000 ​ppm MgCl2 and LiCl mixture), which is the highest value achieved among polyamide-based nanofiltration membranes. In addition, the membranes exhibited good stability in 40 ​h’ continuous testing. The modification strategy proposed in the present work is highly compatible with current industrial membrane preparation processes and easy to scale up with cost effectiveness.

Lithium intercalation and deintercalation of thermally decomposed LiAl2-layered double hydroxides

Lithium aluminum layered double hydroxide (LiAl2-LDH) nanocrystals on aluminum metal substrates were synthesized to adsorb lithium in aqueous solutions and utilized to collect lithium in aqueous media. LiAl2-LDH is transformed at 300 °C into a mixture of LiCl and Li-Al-O-OH; dissolved lithium in deionized water at 25 °C reached 85% compared to the intercalated lithium content. Amorphous Li-Al-O-OH residues on the aluminum metal substrate were capable of adsorbing lithium ions back to the lithium rich LiAl2-LDH phase. Thermal treatment followed by additional lithium intercalation suggested a topotactic reaction of lithium ions between amorphous Li-Al-O-OH and LiAl2-LDH. We also proposed a facile recycling method of lithium ions by peeling off the Li-Al-O-OH layer to save the aluminum metal substrate.

Selective Separation of Lithium Chloride by Organogels Containing Strapped Calix[4]pyrroles

Reported herein are two functionalized crown ether strapped calix[4]pyrroles, H1 and H2. As inferred from competitive salt binding experiments carried out in nitrobenzene-d5 and acetonitrile-d3, these hosts capture LiCl selectively over four other test salts, viz. NaCl, KCl, MgCl2, and CaCl2. Support for the selectivity came from density functional theory (DFT) calculations carried out in a solvent continuum. These theoretical analyses revealed a higher innate affinity for LiCl in the case of H1, but a greater selectivity relative to NaCl in the case of H2, recapitulating that observed experimentally. Receptors H1 and H2 were outfitted with methacrylate handles and subject to copolymerization with acrylate monomers and cross-linkers to yield gels, G1 and G2, respectively. These two gels were found to adsorb lithium chloride preferentially from an acetonitrile solution containing a mixture of LiCl, NaCl, KCl, MgCl2, and CaCl2 and then release the lithium chloride in methanol. The gels could then be recycled for reuse in the selective adsorption of LiCl. As such, the present study highlights the use of solvent polarity switching to drive separations with potential applications in lithium purification and recycling.

Kinetically Stabilized Cation Arrangement in Li3 YCl6 Superionic Conductor during Solid-State Reaction.

The main approach for exploring metastable materials is via trial‐and‐error synthesis, and there is limited understanding of how metastable materials are kinetically stabilized. In this study, a metastable phase superionic conductor, β‐Li3YCl6, is discovered through in situ X‐ray diffraction after heating a mixture of LiCl and YCl3 powders. While Cl− arrangement is represented as a hexagonal close packed structure in both metastable β‐Li3YCl6 synthesized below 600 K and stable α‐Li3YCl6 above 600 K, the arrangement of Li+ and Y3+ in β‐Li3YCl6 determined by neutron diffraction brought about the cell with a 1/√3 a‐axis and a similar c‐axis of stable α‐Li3YCl6. Higher Li+ ion conductivity and lower activation energy for Li+ transport are observed in comparison with α‐Li3YCl6. The computationally calculated low migration barrier of Li+ supports the low activation energy for Li+ conduction, and the calculated high migration barrier of Y3+ kinetically stabilizes this metastable phase by impeding phase transformation to α‐Li3YCl6. This work shows that the combination of in situ observation of solid‐state reactions and computation of the migration energy can facilitate the comprehension of the solid‐state reactions allowing kinetic stabilization of metastable materials, and can enable the discovery of new metastable materials in a short time.

An Aqueous Electrolyte for Fast Energy Storage at -70oC

Sustainable, safe energy storage will be key to fully utilizing renewable power sources and ending the dependence on fossil fuels. One significant limitation of electrochemical energy storage, including batteries and supercapacitors, is performance loss or complete failure at low temperatures. This shortcoming impacts the efficiency of mature technologies such as electric vehicles in cold climates. In more extreme environments, such as in arctic regions and at high altitudes, the development of power-demanding technologies is even more severely limited. Clearly, a means of low temperature energy storage is needed.For commercial lithium-ion batteries, the lower limit of operation is typically -20oC; supercapacitors are more robust and can perform as low as -40oC. At temperatures lower than this, failure occurs at two sites: the electrolyte and the electrode-electrolyte interface. Freezing and/or precipitation of salt species in the electrolyte will typically destroy its ability to carry an ionic current, ceasing redox operation in supercapacitors or batteries. Secondly, the charge transfer resistance at the electrode-electrolyte interface is highly temperature dependent and is another source of low temperature failure, particularly for intercalation type electrodes. Due to these considerations, the design of low temperature energy storage focuses primarily on the electrolyte and the electrode interfaces. The simplest approach is to add a low-freezing solvent (such as dioxolane) to existing organic electrolytes; this solves the issue of electrolyte freezing but not necessarily the increased charge transfer resistance at low temperatures. Other efforts also include developing low-freezing ionic liquid mixtures matched to activated carbons with specially engineered pore distributions to accommodate bulky ions. Such materials enable energy storage down to -70oC, though they are exotic chemicals that have a correspondingly high cost.Perhaps an unlikely candidate for low temperature energy storage are aqueous electrolytes. Despite the growing interest for this safe and low-cost alternative to organic electrolytes, little consideration has been made for these materials in the context of low temperature energy storage, maybe due to the high freezing point of pure water. Here, we find that a mixture of the commodity salt lithium chloride (LiCl) and water forms an excellent low temperature electrolyte, supporting energy storage in supercapacitors as low as -70oC. To the best of our knowledge, the lowest reported performance of an aqueous based energy storage device is -40oC. The electrolyte used here is a eutectic mixture of LiCl (24.8 wt%) in water with a massively depressed freezing point of -74 oC, allowing for high conductivity (~1.83 mS/cm) even at -70oC. Efficient charging of an off-the-shelf activated carbon (Kuraray) at low temperatures demonstrates the practical nature of the electrolyte, possibly owed to the excellent charge-transfer supporting characteristics of water as a solvent. Not only does this aqueous electrolyte support exceptional low-temperature charging kinetics, its stability window is widened from 1.95 to 2.96 V from room temperature to -70oC, making it feasible when compared to organic electrolytes.Taken together, these features highlight the unexpected performance of aqueous electrolytes for low temperature applications. Given the low cost of this electrolyte, it shows great potential for energy storage in arctic regions as well as in high-altitude gliders where energy management must be performed at temperatures as low as -60oC. More broadly speaking, the efficiency (and safety and cost) of electric vehicles could also be vastly improved in cold climates using such a eutectic LiCl electrolyte. Figure 1

Reduction in Formation Temperature of Ta-Doped Lithium Lanthanum Zirconate by Application of Lux–Flood Basic Molten Salt Synthesis

Garnets such as Li7La3Zr2O12 (LLZO) are important Li+ conducting ceramics for potential use as solid electrolytes in solid-state batteries. However, LLZO is predominately prepared by using solid-state reaction methods, despite the high energy cost, multiple steps involved, and large particle sizes of the resultant material. Herein, molten salt synthesis (MSS) is applied to prepare Ta-doped LLZO (Li6.4La3Zr1.4Ta0.6O12, LLZTO), demonstrating that control over the Lux–Flood basicity of the molten salt medium enables drastic reduction in the formation temperature relative to other synthetic methods. Each of the reaction media investigated, including eutectic LiCl–KCl, a mixture of LiCl–LiOH, and highly basic ternary mixtures of LiNO3–LiOH–Li2O2, can be used to synthesize LLZTO under the appropriate experimental conditions. In the last case, garnet powders with predominately submicrometer particle sizes are obtained at temperatures as low as 550 °C. Sintered LLZTO pellets with high room temperature ionic conductivity can be obtained by using powders from each MSS method. LLZTO powders synthesized from the highly basic melts show good densification due to the small particle sizes (0.2–1 μm) and exhibit total ionic conductivity as high as 0.61 mS cm–1. The results show that molten salt synthesis in media with high Lux–Flood basicity is an attractive low-temperature synthetic approach to achieving highly conducting garnet electrolytes.

Molecular Oxygen Activation on Suspended Doped Cerium(IV) Oxide Particles in Molten Chloride Salts

Suspensions of cerium(IV) oxide (CeO2) particles in molten chloride salts were found to be active for molecular oxygen activation when doped with the larger Lanthanides, gadolinium (Gd), praseodymium, (Pr), and samarium, (Sm). The activity for O2 oxidation of gas phase CO on suspended doped ceria in molten mixtures of LiCl–LiBr–KBr and NaCl–KCl is significantly higher than undoped ceria or the salt mixtures alone in the temperature ranges of 350–600 °C, and 700–800 °C, respectively. Surface tension measurements show that the solid doped ceria particles suspended in the melt are contacting the gas–liquid interface of the bubbles. The activity for O2 oxidation of liquid phase MgCl2 in molten MgCl2–KCl to produce Cl2 and solid MgO was also observed to be significantly increased on suspended CeO2 doped with 5 wt% or 10 wt% Gd. The rates of oxidation were observed to increase with catalyst loading.

Synthesis of Selective Sorbent LiCl ⋅ 2Al(OH)3 ⋅ nH2O

A synthesis process of selective layered sorbent LiCl ⋅ 2Al(OH)3 ⋅ nH2O from a mixture of LiCl + AlCl3 + NaOH + H2O solutions with the formation of NaCl solutions in the final suspension with a concentration ranging from 0.5 to 4.0 mol/dm3 has been studied. The effect of various factors exerted on the chemical composition of the sorbent in the course of its synthesis has been analyzed. It is shown that the abrasion strength of the sorbent depends on the amount of NaCl impurities therein. Practical recommendations for the synthesis of the sorbent are given.

Chromium carbide coating of diamond particles using low temperature molten salt mixture

For diamond/metal composite fabrication, coating diamond particles with metal carbide provides improved wettability between the diamond particles and the matrix. In this study, diamond particles were coated with chromium (Cr) using a molten salt method. Diamond and Cr powders were heated at 600–950 °C in molten salts of lithium chloride (LiCl), potassium chloride (KCl), and sodium chloride (NaCl) to create a chromium carbide (here Cr7C3) coating on the diamond particles. Carbide formation was influenced by the diffusion rate and eutectic point of the molten salt mixture. The resulting Cr7C3 coating surface and microstructure were characterized by X-ray diffraction and scanning electron microscopy, respectively. Coating layer thickness was determined using particle size analysis and confirmed by energy dispersive spectroscopy results. A uniform Cr7C3 layer formed on the surface of the diamond particles at a relatively low temperature, at which the graphitization of diamond is avoided. Compared with a mixture of LiCl, KCl, and calcium chloride (CaCl2), which had been used in our previous study, the LiCl–KCl–NaCl mixture increased the reaction rate and initiated coating at a much lower temperature. The differences between the two molten salt mixtures for coating diamond are discussed in terms of the diffusion parameters.

Intermolecular Interactions in N, N-Dimethylacetamide without and with LiCl Studied by Infrared Spectroscopy and Quantum Chemical Model Calculations.

The mixture of LiCl and N, N-dimethylacetamide (DMAc) is an important laboratory-scale solvent for cellulose. However, the mechanism of cellulose dissolution in DMAc/LiCl could not be fully established due to the limited knowledge about the interactions between DMAc and LiCl. To address this issue, we studied neat DMAc and DMAc/LiCl mixtures by ATR FTIR spectroscopy and quantum chemical model calculations. On the basis of the calculations, we newly assigned the bands at 1660 and 1642 cm-1 in the ν(C═O) region of the spectra to DMAc monomeric and dimeric structures. The latter are presumably stabilized by the C-H···O═C weak hydrogen bonds that prevail in both neat DMAc and DMAc/LiCl mixtures. The analysis of the concentrated (7.9 wt % of LiCl) DMAc/LiCl mixture revealed that only about half of DMAc molecules interact directly with LiCl. The resulting average stoichiometry of about 2.8:1 (DMAc:LiCl), indicating the predominance of [(DMAc)2-LiCl] and [(DMAc)3-LiCl] complexes, was found to be temperature independent. Conversely, the stoichiometry was considerably temperature sensitive for the diluted DMAc/LiCl mixture (2.6 wt % of LiCl), indicating that further DMAc molecules can be incorporated into the primary solvation shell of LiCl at higher temperatures. These results highlight the dynamic character of the DMAc/LiCl system that needs to be considered when studying the cellulose dissolution mechanism.

Identification, measurement, and mitigation of key impurities in LiCl-Li2O used for direct electrolytic reduction of UO2

Direct electrolytic reduction (DER) of UO2 utilizes a molten LiCl-Li2O electrolyte operating at 650 °C.Productive processes at the cathode are UO2 and Li2O reduction (followed by metallothermic reduction of UO2 by Li metal). Non-productive reduction current has been observed that could be attributed to impurities produced from interaction of the salt with water. Cyclic voltammetry (CV) scans of molten mixtures of LiCl containing Li2O, LiOH, and/or Li2O2 indicate that LiOH is the primary cause of reduction current preceding UO2 and Li2O reduction. LiOH reduction appears as a broad soluble-soluble transition and forms a pre-reduction plateau characteristic of micro-electrode reactions. Electrochemical response to LiOH in the salt is reduced with addition of Li0, providing a practical approach to eliminating LiOH from LiCl-Li2O salt before the DER process. Generation of H2 gas was detected while heating Li0 with LiCl-Li2O-LiOH, consistent with a reaction mechanism where LiOH reduction causes formation of Li2O and H2.

Wavelength Modulated Back-Scatter Interferometry for Universal, On-Column Refractive Index Detection in Picoliter Volumes.

Wavelength-modulated back scatter interferometry (M-BSI) is shown to improve the detection metrics for refractive index (RI) sensing in microseparations. In M-BSI, the output of a tunable diode laser is focused into the detection zone of a separation channel as the excitation wavelength is rapidly modulated. This spatially modulates the observed interference pattern, which is measured in the backscattered direction. Phase-sensitive detection using a split photodiode detector aligned on one fringe of the interference pattern is used to monitor RI changes as analytes are separated. Using sucrose standards, we report a detection limit of 700 μg/L in a 75 μm i.d. capillary at the 3σ level, corresponding to a detection volume of 90 pL. To validate the approach for electrophoretic separations, Na+ and Li+ were separated and detected with M-BSI and indirect-UV absorbance on the same capillary. A 4 mg/L NaCl and LiCl mixture leads to comparable separation efficiencies in the two detection schemes, with better signal-to-noise in the M-BSI detection, but less baseline stability. The latter arises in part from Joule heating, which influences RI measurements through the thermo-optic properties of the run buffer. To reduce this effect, a 25 μm i.d. capillary combined with active temperature control was used to detect the separation of sucrose, glucose, and lactose with M-BSI. The lack of suitable UV chromophores makes these analytes challenging to detect directly in ultrasmall volumes. Using a 55 mM NaOH run buffer, M-BSI is shown to detect the separation of a mixture of 174 mg/L sucrose, 97 mg/L glucose, and 172 mg/L lactose in a 15 pL detection volume. The universal on-column detection in ultrasmall volumes adds new capabilities for microanalysis platforms, while potentially reducing the footprint and costs of these systems.

Synthesis of Fine Cubic Li7La3Zr2O12 Powders in Molten LiCl–KCl Eutectic and Facile Densification by Reversal of Li+/H+ Exchange

Recently, solid-state electrolytes have been a highly active area of research for future Li-ion batteries due to the potential for drastically improved energy density and safety. Among these materials, garnet structured lithium lanthanum zirconate (Li7La3Zr2O12, LLZO) shows particular promise owing to the high ionic conductivity of its cubic polymorph, inertness, and electrochemical stability against metallic lithium. Herein we report the facile preparation of phase-pure, cubic LLZO via molten salt synthesis in a eutectic mixture of LiCl–KCl at 900 °C. Fine powders of Al- and Ga-doped LLZO were obtained with primary particle sizes ranging from 0.3 to 3 μm. Depending on the consolidation conditions, pellets with up to 86% relative density could be obtained, with Li+ conductivity values ranging from 0.230 to 0.371 mS cm–1. It is also observed that while the effect of hydration has a profoundly deleterious effect on sintering and densification, this effect can be mitigated by the simple addition of LiOH befo...

Continuous dialysis of hydrochloric acid and lithium chloride: permeability of anion-exchange membrane to chloride ions

A counter-current two-compartment dialyzer equipped with an anion-exchange membrane Neosepta-AFN was used to study dialysis of a hydrochloric acid and lithium chloride mixture. To quantify this process, several characteristics were calculated from the data obtained at steady state. First, the dialysis process was characterized by the acid recovery yield and rejection coefficient of salt, which were in the range of 61–98% and 62–94%, respectively (for HCl and LiCl concentrations from 0.1 to 1.0 kmol m−3 and volumetric liquid flow rates from 8 × 10−9 to 24 × 10−9 m3 s−1). Furthermore, this study proved that dialysis of an HCl + LiCl mixture can be quantified by a single characteristic, i.e., the permeability coefficient of the membrane to chloride ions, which is a function of the concentration of both the components in the feed.

High-Speed Observation of Electrolytic Deposition of Liquid Lithium Droplets in LiCl-KCl Melt

In the case of metallothermic reduction of oxide XOx-1(s) (X=Ti, Ta, etc.) by electro-deposited liquid metal Me(=Ca, Li or their alloys), the it accompanied with dissolved Me at the vicinity of the cathode is essential, where the oxide is placed close to the cathode. In this mechanism, the dissolved Me works effectively to reduce XOx-1, even if these solids do not have any direct electronic contact with the cathode. In the case of Li-LiCl-KCl-Li2O system at 723 K, colloidal microparticle dissolution of Li occurs in addition to true dissolution. Recently, the in-situ Raman spectroscopy was carried out, and obtained from colloidal Li were in agreement with the lithium cluster, Li8. The colloidal Li formation strongly depends on the linear current density and that the current concentration should cause its formation. Although colloidal Li occurs at the liquid Li and molten salt interface, the morphology of liquid Li on the electrochemically precipitated cathode surface has not been well understood as root cause. High-speed photography with high-resolution image quality has been becoming possible by recent C-MOS image sensor which has been improved by recent digital optical technology. In this study, we investigated the morphology of liquid Li in molten LiCl-KCl-Li2O by recording electrode surface image obtained with digital microscope at high speed. To elucidate the mechanisms of interfacial morphology on the basis of three-dimensional shape observations, the electric resistance furnace was designed to allow the phenomena occurring within to be observed directly. The changes induced in the interface of electrodes were recorded at a rate of 500 frames per a second (fps) and a resolution of 640 × 480 pixels using a high-speed microscope (the field of view of 610 μm × 460 μm, and the length per pixel of 1.04 μm) was employed. LiCl (>99.0%) and KCl (>99.5%) were used for the melt. The eutectic mixture of LiCl–KCl (= 59:41 mol%, m.p. = 625 K) contained in a borosilicate glass crucible with flat surface was dried under vacuum at 573 K for more than one night to remove residual water and then melted. Li2O (>99.5%) was directly added to the melt as an O2-ion source in the concentration range of 0.1–1.0 mol%. The experimental temperature was 723 K. The interface temperature was measured with a K–type thermocouple with a glass protection tube. All the experiments were conducted in an Ar atmosphere (>99.9995%). The working electrode was a Mo rod (ϕ 1.5 mm, 99.95%) for cyclic voltammetry and it was used as a cathode for electrodeposition of liquid lithium. The counter electrode was a graphite rod (ϕ 10 mm). The Ag+/Ag reference electrode was employed, i.e. a silver wire (ϕ 1.0 mm, 99.99%) was immersed in the LiCl–KCl eutectic melt containing 0.5 mol% AgCl (>99.5%), which was set in a borosilicate tube. Electrochemical measurements were performed using an automatic polarization system (Hokuto Denko Corp., HZ-5000). From the snapshots corresponding to each potential in cyclic voltammograms, blue “fog” was observed are observed at about −2.46 V (vs. Ag+/Ag) with the electrodeposited Li, notably during Li dissolution reaction. The amount of colloidal Li generation decreased by Li2O addition. Chronoamperometry was conducted at -2.55 V vs. Ag+/Ag using a Mo rod electrode for 1.0 s. Photographs of the transient behavior of electrode surface in LiCl-KCl melt are shown in Fig. 1. It can be seen that droplets are formed and grow on the surface of the Mo electrode as the current is generated. It should be noted that the liquid phase precipitates grow heterogeneity on the Mo surface. Considering the “electrocapillary” theory, due to the electrostatic attraction between the droplets charge and charge in the electrode, the energy of their interface is reduced, and the wetting of the electrode should be enhanced. Nevertheless, metal droplets do not wet and spread on the electrode surface completely. Figure 1

Mechanochemistry synthesis of high purity lithium carbonate

A technique for preparing high purity Li2CO3 powders has been developed through mechanochemical process coupled with the dissolution-filtration process. The first step as mechanochemical reaction of both Na2CO3 and LiCl mixtures was designed to obtain the primary Li2CO3 powders using a ball mill. The second step as the dissolution- filtration process was performed to obtain high purity Li2CO3 powders. Experimental results indicate that the three parameters of milling time, rotation speed, and ball-to-sample mass ratio can closely relate with purity of primary Li2CO3 powders. The XRD patterns of primary Li2CO3 powders indicate that mechanochemical reaction of both Na2CO3 and LiCl can be completed in 15 min under optimal conditions at rotation speed as 600 rpm, ball-to-sample mass ratio as 5/1, and molar ratio of Na2CO3 to LiCl as 1/2. The target products of Li2CO3 powders contain impurity of Na+ less than 0.1 mass% with the minimum values as 0.073 mass%. Two shapes of massive particles and smaller grains less than 1 μm in nano scale can be observed in the target products of Li2CO3 powders.

Density and Adiabatic Compressibility of the Immiscible Molten AgBr+LiCl Mixture

Abstract The adiabatic compressibility, β, of the immiscible liquid mixture 0.52 LiCl+0.48 AgBr (the top of the miscibility gap) was experimentally investigated in the temperature range from the melting point to the critical mixing temperature using the sound velocity values, u, measured by the pulse method, and the density quantities, ρ, which were determined using the hydrostatic weight procedure based on the relationship β=u− 2 ρ− 1. It is shown that the coefficients of the temperature dependencies for the compressibility and density of the upper and lower equilibrium phases have opposite signs because of the superposition of the intensity of the thermal motion of the ions and the change in the composition of the phases. The differences, ∆β and ∆ρ, in the magnitudes of the compressibility and density for the equilibrium phases decrease with temperature elevation. The temperature dependencies of the compressibility and density difference are described using the empirical equations ∆β≈(T c–T)0.438 and ∆ρ≈(T c–T)0.439.