Solutions Of Lithium Salts Research Articles

Ion specificity on cysteine tripeptides in aqueous environments revealed by molecular simulation

Molecular dynamics simulations were conducted to investigate the interactions of cysteine tripeptides with ions and water molecules in solutions of salts (MA, M = Li+ and Cs+, A = halide ions). The results revealed that as the anion size increases, cations aggregate more easily around the tripeptide, irrespective of capping. Radial distribution function (RDF) analysis showed direct interactions between F− and tricysteine, whereas Cl−, Br−, and I− exhibited indirect binding. Comparison between Li+ and Cs+ systems indicated that the smaller Li+ ions tend to distribute more around the tripeptide, engaging in direct interactions, whereas Cs+ ions interact indirectly, mediated by water molecules. Interaction energy analysis demonstrated that in lithium salt solutions, the total energy of anions with tricysteine decreased with anion size for both capped and uncapped systems. In cesium salt solutions, the anionic I− had the strongest interaction with cysteine tripeptides, and the cationic Cs+ interaction with tripeptides peaked in the CsI solution. The results highlight differences in ionic interactions depending on the anion-cation correlations of different salts.

Anionic Effects on Concentrated Aqueous Lithium Ion Dynamics.

The dynamics, orientational anisotropy, diffusivity, viscosity, and density were measured for concentrated lithium salt solutions, including lithium chloride (LiCl), lithium bromide (LiBr), lithium nitrite (LiNO2), and lithium nitrate (LiNO3), with methyl thiocyanate as an infrared vibrational probe molecule, using two-dimensional infrared spectroscopy (2D IR), nuclear magnetic resonance (NMR) spectroscopy, and viscometry. The 2D IR, NMR, and viscosity results show that LiNO2 exhibits longer correlation times, lower diffusivity, and nearly 4 times greater viscosity compared to those of the other lithium salt solutions of the same concentration, suggesting that nitrite anions may strongly facilitate structure formation via strengthening water-ion network interactions, directly impacting bulk solution properties at sufficiently high concentrations. Additionally, the LiNO2 and LiNO3 solutions show significantly weakened chemical interactions between the lithium cations and the methyl thiocyanate when compared with those of the lithium halide salts.

INVESTIGATION OF SOLVATION IN LITHIUM PERCHLORATE -PROPYLENE CARBONATE-DIMETHYL CARBONATE SYSTEM BY RAMAN SPECTROSCOPY

The difference of solvent properties can significantly affect the solvation phenomena in individual and, especially, in mixed solutions. In particular, it can be assumed that in mixed solvents, i.e. in systems with intermediate dielectric permittivity (mixtures of linear and cyclic carbonic acid esters), cations will bind molecules of linear esters more strongly and bind molecules of cyclic esters more weakly than it takes place in individual solvents. In the present work the Raman spectra of lithium perchlorate solvents in propylene carbonate (PC), dimethyl carbonate (DMC) and their mixture in a wide range of salt concentrations are studied. It is shown that the solvation effects of the cation are clearly traced in the region of symmetric ring vibrations (~690-730 cm-1) of propylene carbonate and in the region of deformation vibrations of CCA (~520 cm-1) of dimethyl carbonate. These effects are also evident in the mixed solvent. The so-called method of differential spectroscopy was used to judge the structural changes of mixed-solvent systems. It consisted in constructing spectra of lithium salt solutions in mixed solvents, additive sum of spectra of lithium salt solutions in PC and DMC, as well as their difference (differential spectra). The analysis of differential spectra allows us to conclude that in systems with mixed solvent there is a weakening of interaction of propylene carbonate molecules with ions, and there is a preferential solvation of cations and anions by dimethyl carbonate molecules. Also, unlike propylene carbonate, dimethyl carbonate solvates perchlorate ions, which follows from the line contour changes in the region of CH3-group vibrations (2970 cm-1) solvation of anions is also observed in the mixed solvent. For citation: Rabadanov K.Sh., Gafurov M.M., Akhmedov M.A., Rabadanova D.I., Magomedova A.G. Investigation of solvation in lithium perchlorate -propylene carbonate-dimethyl carbonate system by raman spectroscopy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 36-42. DOI: 10.6060/ivkkt.20246705.6967.

Lithium salt post-treatment of anodized 7075-T6 alloy for enhancing corrosion resistance in neutral and acidified NaCl environment

An anodized 7075-T6 aluminum alloy was post-treated in three different lithium salt solutions (Li2CO3, Li2C2O4 or LiNO3) under optimized conditions, respectively, in order to improve corrosion resistance of the alloy in both neutral NaCl (0.05 M, pH = 6.5) and acidified NaCl (0.6 M, pH = 3.5) solutions. The results indicate that the porous anodic film can be effectively sealed by the post-treatment and the sealing products are a mixture of boehmite, Li–Al amorphous hydroxides and Li–Al-LDH, with the relative proportion of each component varying with the sealing conditions. All lithium salt treated alloy specimens passed 1100 h of neutral salt spray test, and the Li2C2O4-based alloy specimen exhibited higher corrosion resistance than others in the neutral NaCl environment. Although the corrosion resistance of the coating deteriorated in the acidified NaCl solution, the lithium salt treated alloy specimens still showed distinct advantage over the hot water sealed counterpart, especially for the LiNO3-based process.

Exploring lithium salt solution in sulfone and ethyl acetate-based electrolytes for Li-ion battery applications: a molecular dynamics simulation study

The design of lithium-ion batteries (LIBs) by introducing novel electrolytes is an interesting research topic in electrochemistry, due to the necessity of using LIBs to fight against the energy crisis and environmental pollution.

Manipulating the Nanophase Separation of a Polymer-Salt Microfluid Generates an Advanced In Situ Separator for Component-Integrated Energy Storage Devices.

A polymer separator plays a pivotal role in battery safety, overall electrochemical performance, and cell assembly process. Traditional separators are separately produced from the electrodes and dominated by porous polyolefin thin films. In spite of their commercial success, today's separators are facing growing challenges with the increasing demand on the device safety and performance. As an attempt to address this urgent need, here, we propose a concept of in situ separator technology by manipulating the two-dimensional (2D) microfluid nanophase separation (2D-MFPS) of a poly(vinylidene difluoride)/lithium salt solution during drying. Particularly, nanophase separation is effectively regulated by low humidity, salt type, and compositions. For application studies, this 2D-MFPS is directly performed onto commercial electrodes under drying conditions with low humidity to fabricate a high-performance in situ separator with thickness and porous structures comparable to those of commercial Celgard separators. This in situ separator shows superior performance in high-temperature stability and wetting capability to a variety of liquid electrolytes. Finally, pouch cells with this in situ separator technology are successfully assembled with an extremely simplified separator-stacking-free process and demonstrate stable cycle performance due to the well-controlled porous structures and electrode-separator interface.

Физико-химические свойства растворов перхлората и тетрафторбората лития в смеси сульфолана и сернистого ангидрида

The temperature dependencies of physical and chemical properties (viscosity, density, electrical conductivity) and the melting temperature of 1M solutions of lithium salts (LiClO4 and LiBF4) in the mixture of sulfolane and sulfurous anhydride (∼1M) were studied. It was shown that the introduction of 1M (5% wt.) of sulfurous anhydride into 1M solutions of LiClO4 and LiBF4 in sulfolane increased the specific and corrected electrical conductivity, densities, activation energy of electrical conductivity and viscous flow of electrolyte solutions; and reduced viscosity and melting temperatures.

Determination of the phase transition of solutions of lithium salts in sulfolane by the molecular dynamics method

Determination of the phase transition of solutions of lithium salts in sulfolane by the molecular dynamics method

Polysulfide Rejection Strategy in Lithium-Sulfur Batteries Using an Ion-Conducting Gel-Polymer Interlayer Membrane.

Lithium-sulfur batteries (LiSBs) are emerging as promising alternative to conventional secondary lithium-ion batteries (LiBs) due to their high energy density, low cost, and environmental friendliness. However, preventing polysulfide dissolution is a great challenge for their commercial viability. The present work is focused on preparing a lithium salt and ionic liquid (IL) solution (SIL) impregnated ion (lithium ion)-conducting gel-polymer membrane (IC-GPM) interlayer to prevent polysulfide migration toward the anode by using an electrostatic rejection and trapping strategy. Herein, we introduce an SIL-based freestanding optimized IC-GPM70 (70 wt % SIL) interlayer membrane with high lithium-ion conductivity (2.58 × 10-3 S cm-1) along with excellent thermal stability to suppress the migration of polysulfide toward the anode and prevent polysulfide dissolution in the electrolyte. Because of the coulombic interaction, the anionic groups, -CF2 of the β-phase polymer host PVdF-HFP, TFSI- anion of IL EMIMTFSI, and anion BOB- of LIBOB salt, allow hopping of positively charged lithium ions (Li+) but reject negatively charged and relatively large-sized polysulfide anions (Sx-2, 4 <x <8). The cationic group EMIM+ of the IL is electrostatically able to attract and trap the polysulfides in the interlayer membrane. Since the shuttle effect of lithium polysulfides in LiSBs has been suppressed by the prepared IC-GPM70 interlayer, the resulting lithium-sulfur cell exhibits significantly higher cycling stability (1200 cycles), rate performance (1343, 1208, 1043, 875, and 662 mAh g-1 at 0.1C, 0.2C, 0.5C, 1C, and 2C, respectively), and structural integrity during cycling than its counterpart without the IC-GPM70 interlayer. The interlayer membrane has been found to improve the performance and durability of LiSBs, thus making them a viable alternative to conventional LiBs.

Lithium salts as active corrosion inhibitors for aluminum substrates

As an effort to replace carcinogenic chromate from protective coatings, researchers are continuously searching and proposing new non-toxic chemicals sharing similar properties: leachable, responsive, and film-forming. Lithium (Li), in the form of either a salt additive in coatings or alloyed with aluminum (Al), is observed to be able to form insoluble protective layers and thus reduce the corrosion rate of the Al substrates. The protective film formed is often composed of Li, Al, carbonate (CO3), hydroxide (OH) etc., sharing similar structure to a layered double hydroxide (LDH) as indicated by several mechanistic studies. The successful formation of the irreversible/insoluble protective film requires oxygen, correct pH, and the right combination of available ion species. In this study, electrochemical impedance spectroscopy (EIS) results show that these leachable inhibitor coatings yield poor barrier properties before and after artificial weathering. Scanning electron microscopy pictures show the growth of an inorganic layer between the coating and aluminum substrate, indicative of the formation of a layered double hydroxide (LDH) structure. Current mapping generated by scanning vibrating electrode technique (SVET) indicates that aerated lithium salt solutions can cause pitting corrosion over bare aluminum, while organic coatings pigmented with lithium were able to keep the surface relatively passive, with and without the presence of a defect. An anodic shift of the surface of the organic coatings pigmented with lithium containing a defect is seen while keeping the surface relatively passive, indicating anodic passivation of the metal surface.

Sulfur solubility in sulfolane electrolytes for lithium-sulfur batteries

The solubility of sulfur in sulfolane and sulfolane solutions of lithium salts [LiBF4, LiClO4, LiPF6, LiSO3CF3 and LiN(SO2CF3)2], promising electrolytes for lithium-sulfur batteries, was determined by UV-vis spectroscopy. It was found that the solubility of sulfur in sulfolane at 30°C is 82.0 mM, and in sulfolane solutions of lithium salts (1 M) is 4-9 times lower than in pure sulfolane. The dependence of sulfur solubility on the concentration of lithium salts is not linear, it is 32.9 and 5.8 mM for sulfolane solutions of 0.5 М LiClO4 and 2.35 M LiClO4, respectively.

Understanding hydrogen adsorption performance of lithium-doped MIL-101(Cr) by molecular simulations: Effects of lithium distribution

Metal-organic frameworks (MOFs) have been recognized as one of the most compelling physical adsorption hydrogen storage materials owing to their ultrahigh surface area and excellent hydrogen adsorption performance. In order to further improve their hydrogen adsorption performance, lithium doping is an effective approach to increase the number of hydrogen adsorption sites as well as enhance the interaction strength towards hydrogen molecules according to grand canonical Monte Carlo(GCMC) simulations. However, in previous simulation studies, lithium ions were commonly assumed to be randomly distributed in MOF frameworks. In fact, the lithium-doped MOFs were prepared by immersing MOFs in a lithium salt solution and then drying them under high temperatures, in which the distribution of Li+ in MOF frameworks is elusive. In this work, the lithium-doped MIL-101 models (i.e., Immersion model) with varying lithium contents were constructed according to experimental operation and their hydrogen adsorption performance from GCMC simulations was also investigated in comparison with the equivalent models with randomly distributed lithium ions (i.e., Random model). It is found that in contrast to the uniform distribution of lithium ions in Random model, the accumulation of lithium ions was inspected in Immersion models especially at high loadings, leading to the reduced pore size. On the contrary, the hydrogen adsorption capacities of Immersion models are significantly improved owing to the enhanced interaction strength with hydrogen molecules resulting from the reduced pore size and the strengthened charged-induced dipole interaction.

Thermodynamic modeling of aqueous lithium salt solutions with association electrolyte nonrandom two-liquid activity coefficient model

The high charge density of lithium ion and the resulting strong association phenomena make thermodynamic modeling of aqueous lithium electrolyte solutions extremely challenging. In this study, the association electrolyte nonrandom two-liquid activity coefficient model of Lin et al. (AIChE J. 2022, 68(2), e17422) is utilized to correlate and predict thermodynamic properties and solubility behavior of aqueous single electrolyte solutions of LiCl, LiBr, LiI, and LiNO3, and their mixed electrolyte solutions. Capturing self-association of water, cross-association of ion and water for hydration, and cross-association of cation and anion for ion-pairing, the association model accurately represents the literature experimental data up to saturation concentrations and at the temperature ranging from 263 K to 523 K. This study further investigated the effect of anions of the lithium salts, and re-confirmed that the order of solution non-ideality as LiI > LiBr > LiCl > LiNO3 because the anions with stronger association strengths are more likely to form ion pairs and thus lower the mean ionic activity coefficients.

Corrosion Behavior of Type 304 Stainless Steels in Highly Concentrated Lithium Salt Solutions

Corrosion Behavior of Type 304 Stainless Steels in Highly Concentrated Lithium Salt Solutions

Electrodialysis for the Concentration of Lithium-Containing Brines-An Investigation on the Applicability.

The importance of lithium as a raw material is steadily increasing, especially in the growing markets of grid energy and e-mobility. Today, brines are the most important lithium sources. The rising lithium demand raises concerns over the expandability and the environmental impact of common mining techniques, which are mainly based on the evaporation of brine solutions (Salars) in arid and semiarid areas. In this case, much of the water contained in the brine is lost. Purification processes lead to further water losses of the ecosystems. This calls for new and improved processes for lithium production; one of them is electrodialysis (ED). Electrodialysis offers great potential in accessing lithium from brines in a more environmentally friendly way; furthermore, for the recovery of lithium from spent lithium-ion batteries (LIB), electrodialysis may become a vital technology. The following study focused on investigating the effect of varying brine compositions, different ED operation modes, and limiting factors on the use of ED for concentrating lithium-containing brine solutions. Synthetic lithium salt solutions (LiCl, LiOH) were concentrated using conventional ED in batch-wise operation. While the diluate solution was exchanged once a defined minimum concentration was reached, the concentrate solution was concentrated to the respective maximum. The experiments were conducted using a lab-scale ED-plant (BED1-3 from PCCell GmbH, Germany). The ion-exchange membranes used were PCSK and PCSA. The treated solutions varied in concentration and composition. Parameters such as current density, current efficiency, and energy requirements were evaluated. ED proved highly effective in the concentration of lithium salt solutions. Lithium chloride solutions were concentrated up to approximately 18-fold of the initial concentration. Current efficiencies and current densities depended on voltage, concentration, and the composition of the brine. Overall, the current efficiencies reached maximum values of around 70%. Furthermore, the experiments revealed a water transport of about 0.05 to 0.075% per gram of LiCl transferred from the diluate solution to the concentrate solution.

Solvate Ionic Liquids: Assessing the Possibility of Determining the Composition by Means of Gas–Liquid Chromatography

A study is performed of the possibility of using gas–liquid chromatography (GLC) to determine the composition of solutions of lithium salts in aprotic dipolar solvents and solvate ionic liquids. The objects of study are solutions of lithium perchlorate and lithium trifluoromethanesulfonate in sulfolane and solvate complexes of lithium perchlorate with sulfolane obtained in two ways: direct interaction of the initial components in a given molar ratio and interaction of the components in a common solvent with its subsequent removal via evaporation. It is shown that GLC is a convenient way of determining the content of a solvating solvent in the composition of solutions and solvate ionic liquids. The presence of lithium salt in the analyzed solutions does not affect the period of retention; instead, it raises the degree of asymmetry of the chromatographic peak of the solvent and manifestation of the tailing effect. It is found that the presence of salt in the considered system also does not reduce the accuracy of determining the solvent content. The error in determining the content of solvent in solutions of lithium salts and solvate complexes by GLC is no greater than 1%.

Probing Nuclear Dipole Moments and Magnetic Shielding Constants through 3-Helium NMR Spectroscopy

Multinuclear NMR studies of the gaseous mixtures that involve volatile compounds and 3He atoms are featured in this review. The precise analyses of 3He and other nuclei resonance frequencies show linear dependencies on gas density. Extrapolation of the gas phase results to the zero-pressure limit gives the ν0(3He) and ν0(nX) resonance frequencies of nuclei in a single 3-helium atom and nuclei in molecules at a given temperature. The NMR frequency comparison method provides an approach for determining different nuclear magnetic moments. The application of quantum chemical shielding calculations, which include a more complete and careful theoretical treatment, allows the shielding of isolated molecules to be achieved with great accuracy and precision. They are used for the evaluation of nuclear moments, without shielding impacts on the bare nuclei, for: 10/11B, 13C, 14N, 17O, 19F, 21Ne, 29Si, 31P, 33S, 35/37Cl, 33S, 83Kr, 129/131Xe, and 183W. On the other hand, new results of nuclear moments were used for the reevaluation of absolute nuclear magnetic shielding in the molecules under study. Additionally, 3He gas in water solutions of lithium and sodium salts was used for measuring 6/7Li and 23Na magnetic moments and reevaluating the shielding parameters of Li+ and Na+ water-solvated cations. In this paper, guest 3He atoms that play a role in probing the electron density in many host macromolecules are also presented.

High performance of polyethylene composite separators modified by carbon nanotube, lithium salt and SiO2 nanoparticles for lithium ion batteries

In this work, the polyethylene (PE) separator is firstly modified with bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) solution, and then coated with a solution of hydroxyl functionalized carbon nanotube (CNT), nano-SiO2 and polyvinyl alcohol (PVA) on its one side. The obtained composite separator (PE@LiSiO2CNT) is with a thermal shrinkage of 14% at 150 °C for 0.5 h, and the ionic conductivity can be as high as 1.69 × 10-3 S cm-1. Furthermore, the specific discharge capacity of the assembled lithium ion batteries (LIBs) reaches 164 mAh g-1 at 0.2 C, and the coulomb efficiency remains above 99% after 250 cycles. This can be attributed to the network structure of SiO2 and CNT which increases the porosity of the separator and improves the electrolyte uptake. Besides, the CNT effectively alleviates the self-aggregation of SiO2, and promotes the rapid electrochemical reactions between the separator and the cathode. And it can also allow the free diffusion of lithium ions through its walls and channels with high efficiency, thus reducing the charge transfer resistance and improving the battery performance. Therefore, the modified separator with excellent dimensional thermal stability and electrochemical performance are successfully obtained, which are helpful to the development of LIBs.

Natural Pigment from Madder Plant as an Eco-Friendly Cathode Material for Aqueous Li and Na-Ion Batteries

Modifying commercial Li-ion batteries to become more environmentally friendly is of a growing concern. This paper provides an examination of a potential replacement for commercial cathode material using a naturally occurring purpurin in aqueous solutions of lithium and sodium salts. The purpurin is extracted from the Madder plant (Rubia tinctorum) and characterized through XRPD, FTIR, and SEM methods. The intercalation and de-intercalation capacities obtained for the purpurin as a cathode material in the aqueous solution of LiNO3 are approximately 40 mAh g−1. Compared to the capacity of ∼35 mAh g−1 obtained for commercially used transition metal oxides in an aqueous solution of Li salt, results presented make the purpurin a promising material for the “green” development of Li-ion batteries. Although the initial purpurin capacity in NaNO3 solution is almost doubled (∼73 mA h g−1) compared to that of Li-salt, it is unstable and fades during cycling. The possible explanation of the electrochemical behavior of purpurin as the cathode material in aqueous solutions of Li and Na salts is discussed in detail.

Elucidating the mechanism behind the infrared spectral features and dynamics observed in the carbonyl stretch region of organic carbonates interacting with lithium ions.

Ultrafast infrared spectroscopy has become a very important tool for studying the structure and ultrafast dynamics in solution. In particular, it has been recently applied to investigate the molecular interactions and motions of lithium salts in organic carbonates. However, there has been a discrepancy in the molecular interpretation of the spectral features and dynamics derived from these spectroscopies. Hence, the mechanism behind spectral features appearing in the carbonyl stretching region was further investigated using linear and nonlinear spectroscopic tools and the co-solvent dilution strategy. Lithium perchlorate in a binary mixture of dimethyl carbonate (DMC) and tetrahydrofuran was used as part of the dilution strategy to identify the changes of the spectral features with the number of carbonates in the first solvation shell since both solvents have similar interaction energetics with the lithium ion. Experiments showed that more than one carbonate is always participating in the lithium ion solvation structures, even at the low concentration of DMC. Moreover, temperature-dependent study revealed that the exchange of the solvent molecules coordinating the lithium ion is not thermally accessible at room temperature. Furthermore, time-resolved IR experiments confirmed the presence of vibrationally coupled carbonyl stretches among coordinated DMC molecules and demonstrated that this process is significantly altered by limiting the number of carbonate molecules in the lithium ion solvation shell. Overall, the presented experimental findings strongly support the vibrational energy transfer as the mechanism behind the off-diagonal features appearing on the 2DIR spectra of solutions of lithium salt in organic carbonates.