Lithium Melts Research Articles

Modification of the refractive index of lithium niobate crystals by transmission of high-energy He2+4 and D+ particles

We report reductions of the refractive index of congruently melting lithium niobate crystals of up to 6×10−3 by exposure of z-cut samples with high-energy 4He2+ and D+ particles which are transmitted through the crystals.

Poling dynamics of lithium niobate crystals

Ferroelectric domain reversal via electric field poling of congruently melting lithium niobate (LiNbO3) crystals is investigated. An electro-optic interferometric observation technique reveals spatial and temporal dynamics of the poling process. Starting from seeds, the domains grow until the entire crystal has a switched polarization. During the switching process the boundaries are preferentially aligned along the crystallographic axes. The coercive field between two sequenced domain inversions is transiently reduced after a poling event, and recovers exponentially with a time constant of about half a minute. No light-induced change of the recovery time constant, neither with green nor with ultraviolet light, is observed. The results are of relevance for domain engineering of LiNbO3 crystals.

Mechanism of reaction synthesis of Li-B alloys

A model for reaction synthesis of Li-B alloys has been presented. Results show that the first exothermal reaction can be divided into three stages. The first stage is an instantaneous reaction on the boundary between boron particles and lithium melting, in which the caloric released is inversely proportional to the particle size of the boron powder. The second stage is a reaction between the unreacted boron and the lithium that diffuses through the product LiB 3 on the surface of the boron particle. This process can be described by Johnston model. The third stage is dissolution of the product LiB 3 to Li liquid, which takes place at temperature up to 420℃. At the same time, the second exothermal reaction begins, which consists of nucleation and growth of the last Li-B compound. It can be divided into two substages, i.e. the nucleation pregnant stage and the exploded reaction stage. When the concentration of the particle nucleated is high enough, an exploding reaction takes place. The lower the temperature, the longer the time needed for the exploding reaction. By the model presented, the experimental phenomena in the synthesis are explained.

Mixed solvent electrolytes containing fluorinated carboxylic acid esters to improve the thermal stability of lithium metal anode cells

A safety aspect is one of the most important problems to utilize lithium metal anode battery which can show significant higher capacity than conventional lithium ion battery. The thermal stabilities of electrolytes containing fluorinated carboxylic acid esters were assessed at the coexistence of lithium metal using differential scanning calorimeter. Among the fluorinated carboxylic esters used here, CHF 2COOCH 3 (Methyl difluoro acetate; MFA) exhibited the highest onset temperature and smallest amount of exothermic heat at the coexistence of lithium. A similar trend was observed for apparent 1-M solution of LiPF 6 with fluorinated carboxylic acid esters and ethylene carbonate (EC)+dimethyl carbonate (DMC) (1:1 in vol.). Precise thermal study was undertaken for 1 M LiPF 6/MFA and 1 M LiPF 6/EC+DMC or propylene carbonate (PC), changing the mixing ratio at the coexistence of lithium metal. Surviving lithium metal content was estimated by endothermic vs. exothermic heat ratio at lithium melting and freezing from 300 °C. With the increase of volume ratio of MFA from 0% to 100%, the amount of surviving lithium metal increased from 0% to 95%.

Alternative Diffusant Sources for Metallization from the Liquid Phase

We describe some results of experimental verification of the expediency of using metal oxides Nb2O5, Cr2O3, W2O5, MoO2, NiO, etc. as a diffusant source in order to intensify the application of coatings in sodium and lithium melts. We investigate some specific features of the formation of chromium coatings, obtained in lithium from Cr2O3, as well as their chemical and phase composition, structure, and physicomechanical properties. We show that chromizing in Li-Cr2O3 medium proceeds 1.5–2 times as fast as in Li-Cr and guarantees satisfactory wear and corrosive resistance of steel articles.

Abuse Testing of Lithium-Ion Batteries: Characterization of the Overcharge Reaction of LiCoO2/Graphite Cells

The short-circuit and overcharge behavior of prismatic lithium-ion batteries containing cathodes and graphite anodes were studied in detail. Internal thermocouples were used to characterize the thermal profiles of the cells under abusive conditions. Differences between the internal and surface temperatures of the cells during the safety tests highlighted the importance of the internal measurement for obtaining more meaningful data. Under short-circuit conditions the cells remained hermetically sealed, reached an internal temperature of 132°C (the shutdown temperature of the separator), and then slowly cooled to ambient temperature. However, on extreme overcharge testing different results were obtained depending on the current used to charge the battery. At low currents the cells remained hermetic, but swelled significantly. When higher currents were used, the cells ruptured during overcharge. Experimental cells were constructed with a systematic variation in cell balance and the point of cell rupture tracked to the amount of cathode in the cell, independent of the amount of anode material. The internal dc resistance of the cell was also measured during the overcharge reaction and remained low throughout most of the test, although a large increase was observed at the end of the test due to the melting of the shutdown separator. The cells overcharged with high currents all reached high temperatures immediately prior to rupturing, which suggests that the melting of lithium is a key underlying factor leading to the rupture of the cells. To test this proposal, cells were assembled with lithium removed from the cathode, so that lithium metal would not plate on the anode during the overcharge test. These cells reached a significantly higher temperature prior to rupture. © 2001 The Electrochemical Society. All rights reserved.

A pH Electrode Based on Melt-Oxidized Iridium Oxide

Fabrication and characterization of a novel potentiometric pH electrode based on melt-oxidized iridium oxide film is presented. The oxide film produced in a lithium carbonate melt has the composition of and shows high chemical stability. The electrode based on this oxide film exhibits very promising pH sensing performance, with an ideal Nernstian response in the tested pH range of 1 to 13. The potential response is fast, with a 90% response time obtained in less than 1 s for all pH changes. The open-circuit potential of the electrode is almost drift-free, with an average variation over time in a pH 6.6 solution as small as 0.1 mV/day. Furthermore, the potential/pH slopes and the apparent standard electrode potentials show excellent agreement among electrodes from the same batch. A comparison is made of the present electrode and those reported in the literature with respect to fabrication method and pH sensing characteristics. © 2001 The Electrochemical Society. All rights reserved.

Thermal Stability Studies of Li‐Ion Cells and Components

Thermal stability of fully charged 550 mAh prismatic Li‐ion cells (Sn‐doped carbon) and their components are investigated. Accelerating rate calorimetry (ARC) is used to determine the onset temperature of exothermic chemical reactions that force the cell into thermal runaway. Differential scanning calorimetry (DSC) and thermogravimetry analysis are used to determine the thermal stability of the cell's positive electrode (PE) and negative electrode (NE) materials from 35 to 400°C. The cell self‐heating exothermic reactions start at 123°C, and thermal runaway occurs near 167°C. The total exothermic heat generation of the NE and PE materials are 697 and 407 J/g, respectively. Heat generations of the NE and PE materials, washed in diethyl carbonate (DEC) and dried at ≈65°C under vacuum, are significantly lower than unwashed samples. Lithium plating increases the heat generation of the NE material at temperatures near the lithium melting point. Comparison of the heat generation profiles from DSC and ARC tests indicates that thermal runaway of this cell is close to the decomposition temperature range of the unwashed PE material. We conclude that the heat generation from the decomposition of PE material and reaction of that with electrolyte initiates thermal runaway in a Li‐ion cell, under thermally or abusive conditions. © 1999 The Electrochemical Society. All rights reserved.

Tritium barrier development for austenitic stainless steel by its aluminizing in a lithium melt

A technique for obtaining coatings on a 0.12%C/18%Cr/10%Ni/Ti austenitic stainless steel by its aluminizing in melts of the following composition x%Al+(100%− x)%Li( x=3, 10) at the temperature range 870–1070 K for 5–100 h has been developed. An investigation in to the decrease in the tritium penetration through the steel has been carried out. It has been shown that two-side aluminizing of the steel in the 10%Al/90%Li melt at 870 and 970 K for 5 h decreases its tritium permeability by more than three orders of magnitude. Furthermore, aluminizing the steel under these regimes reduces its erosion coefficient by one order of magnitude on average due to radiation blistering, decreases its coefficient of physical sputtering by more than 2.5 times and protects the steel from failure under the action of hydrogen pulsed plasma fluxes with the incident flux specific power up to 4–5·10 10 W m −2 and a pulse duration of 10–50 μs. The mechanisms of decreasing the tritium permeation with regard to the surface relief forming under the treatment have been discussed.

Dissolution of Boron in Lithium Melt

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDissolution of Boron in Lithium MeltAnton Meden, Janez Mavri, Marjan Bele, and Stane PejovnikCite this: J. Phys. Chem. 1995, 99, 12, 4252–4260Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://doi.org/10.1021/j100012a055RIGHTS & PERMISSIONSArticle Views337Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (4 MB) Get e-Alerts

The defect structure of congruently melting lithium niobate

Six samples of congruently melting lithium niobate (∼Li0.95Nb1.01O3) have been examined by powder x-ray diffraction for the occurrence of niobium antisite defects (niobium on lithium sites). Contrary to current thinking, we have found no evidence for the occurrence of high concentrations of such defects, which also require the presence of Nb site vacancies. Rather, it was found that the number of antisite defects is close to the minimum that is required to sustain charge neutrality in a model of the type ([Li1−xNbx/5][Nb]O3), where the Nb site is fully occupied.

Impedance Analysis for Oxygen Reduction in a Lithium Carbonate Melt: Effects of Partial Pressure of Carbon Dioxide and Temperature

Effects of partial pressure of carbon dioxide and temperature on oxygen reduction kinetics on a gold electrode in a lithium carbonate melt were examined using electrochemical impedance spectroscopic (EIS) and linear sweep voltammetric techniques. The impedance spectra were analyzed by a complex nonlinear least squares method, using the Randles‐Ershler equivalent circuit model, to determine the electrode‐kinetic and the mass‐transfer parameters such as the charge‐transfer resistance and the Warburg coefficient. The cyclic voltammetric measurements indicated that the oxygen reduction process in lithium carbonate melt is “reversible” up to 200 mV/s. The product determined by cyclic voltammetry agreed well with those estimated by the EIS method. The reaction order with respect to carbon dioxide and the activation energy for the exchange current density were determined to be −0.52 and 132 kJ/mol, respectively. Also, the reaction order with respect to carbon dioxide and the activation energy for were calculated to be −0.8 and 185 kJ/mol, respectively.

DSC analysis of the reaction between lithium and boron

The reaction between lithium and boron has been followed by differential scanning calorimetry and X-ray powder diffraction in the temperature range 25–1050°C. After melting of lithium at 180°C, the exothermal solvation of boron in liquid lithium at about 350°C was observed. At approximately 450°C, the exothermal reaction begins, giving LiB · xLi which decomposes above 900°C to yield LiB.

Impedance Analysis for Oxygen Reduction in a Lithium Carbonate Melt

Oxygen reduction on a smooth gold electrode in a pure lithium carbonate melt was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The impedance data were analyzed using the Randles‐Ershler equivalent circuit to determine parameters such as the charge‐transfer resistance, Warburg coefficient, double‐layer capacity, and uncompensated electrolyte resistance. The parameters estimated by complex plane plots and a complex nonlinear least squares method are in good agreement. Cyclic voltammetric measurements showed that oxygen reduction in a lithium carbonate melt is very rapid. A mass transfer parameter, , estimated by the cyclic voltammetry concurred with that calculated by the electrochemical impedance spectroscopy technique. The temperature dependences of the exchange current density and the product were examined, and the apparent activation energies were determined to be, respectively.

Electrode Kinetics of Oxygen Reduction in Lithium Carbonate Melt: Use of Impedance Analysis and Cyclic Voltammetric Techniques to Determine the Effects of Partial Pressure of Oxygen

The effects of the partial pressure of oxygen and temperature on the oxygen reduction on a submerged gold electrode in a lithium carbonate melt were investigated using cyclic voltammetry and impedance analysis. The values for the mass‐transfer parameters, , obtained from cyclic voltammetry and impedance analysis were in good agreement. The reaction orders for oxygen at 800°C were calculated to be about 0.3 for the exchange current density and 0.5 for the product; these values are consistent with the mechanism proposed in the literature for oxygen reduction in melt.

Impedance Analysis of Oxygen Reduction in Lithium Carbonate Melt: Effect of Partial Pressure of Carbon Dioxide

Impedance Analysis of Oxygen Reduction in Lithium Carbonate Melt: Effect of Partial Pressure of Carbon Dioxide

Effect of water in an Li/sub 2/O bed on tritium inventory

Lithium oxide (Li/sub 2/O) has the most potential among various solid breeder material candidates because of its high lithium density and melting point. The phase relationship of Li/sub 2/O and H/sub 2/O vapor is important in understanding the way tritium is released from Li/sub 2/O and in estimating the tritium inventory in the blanket. The phase equilibrium for a Li/sub 2/O-LiOH-H/sub 2/O system and for water adsorption on and absorption in Li/sub 2/O are studied in the 620 to 1020 {Kappa} temperature range, and a phase diagram is proposed in this paper based on the data obtained. Furthermore, the tritium inventory in a water-cooled blanket packed with Li/sub 2/O pellets is estimated using the data obtained.

Preparation, structure and ionic conductivity of lithium phosphide

Lithium phosphides (LiP and Li 3P) were synthesized by the exothermic reaction between lithium melt and phosphorus powder in an inert atmosphere. The structure of these compounds was studied using X-ray diffraction and elemental analysis. LiP crystallizes in a monoclinic structure and has a black metallic luster. Li 3P crystallizes in a hexagonal structure and has brown color. LiP is an insulator, but Li 3P shows ionic conductivity higher than 10 −4 (Ω cm) −1 at ambient temperature. Li 3P has a good stability in contact with a lithium electrode and acts as a membrane for lithium transport without phase transformation. Lithium phosphide may have potential application as an electrolyte for solid state devices.

Viscosity and density measurements of molten lithium niobate

Abstract The viscosity and density of a congruently melting lithium niobate liquid were measured from 1270 to 1370°C. The viscosity displayed an Arrhenius behavior with an activation energy of 23.8 to 41.5 kJ/mol, depending on the shear rate. The liquid showed non-Newtonian behavior with viscosity increasing with shear rate. The results were not influenced by changing the atmosphere from air to pure oxygen or pure nitrogen. The viscosity data at 1270°C range from 19 to 34 cP, again depending on the shear rate. The density of the liquid was approximately 3.63 g/cm3 in this temperature range with a thermal expansion of 2.0×10-4/°C.

Preparation, Characterization and Conductivity of Li3N, Li3P and Li3As

AbstractThe superionic conductors lithium nitride and lithium phosphide and the semi-metallic conductor lithium arsenide were synthesized through elemental reactions of lithium melt with nitrogen gas and phosphorus or arsenic powders. A high mobility of the lithium ion was found in this class of compounds. These compounds are hard and brittle and have a dark brown color. The structures of these compounds were studied using x-ray diffraction techniques. All three compounds crystallize in a hexagonal structure with a P6/mm space group. The lattice dimensions expand anisotropically as the size of the anion increases.The ionic and electronic conductivities of the compounds were studied using reversible lithium electrodes and an ion blocking molybdenum electrode. The temperature dependent conductivity measurements (Arrhenius plot) show a high ionic and a negligible electronic conductivity for both lithium nitride and lithium phosphide. However, lithium arsenide shows semi-metallic behavior with a high electronic conductivity. A higher degree of covalency in the ct direction and a more ionic character in x-y plane were observed. The anisotropic nature of the chemical bonds in these compounds provides a shallow potential well in x-y plane and allows the correlated motion of lithium ions.Lithium phosphide and nitride are superionic conductors and useful materials for application in batteries and sensors. Lithium nitride decomposes below 0.5 volts and can be used in low voltage and zero current devices. Lithium phosphide is stable up to 2.2 volts and can be used for higher voltage devices. These compounds decompose in contact with water and are air sensitive.