Lithium Solutions Research Articles

Understanding Mg/S Batteries: The Different Electrochemistry of Lithium and Magnesium Polysulfide Solutions

Lithium/sulfur batteries are considered as one of the most promising post-lithium-ion battery systems, because the high specific capacity of sulfur drastically outranges the capacities of Li-ion insertion cathodes. However, at the Li metal anode, dendrite formation and a high reactivity towards the electrolyte lead to lifetime and safety concerns.[1] In order to circumvent these issues while maintaining high specific capacities, magnesium/sulfur batteries are increasingly studied.[2] In contrast to Li, the Mg metal anode enables homogeneous Mg deposition and dissolution at up to 100% Coulombic efficiency. In addition, Mg is much cheaper and highly abundant. In Li/S and Mg/S cells, charge and discharge of the sulfur cathode proceeds through a cascade of bivalent Sx 2- and radical Sy •- polysulfide intermediates. The individual polysulfide chemistries thus determine the accessibility and performance of both battery systems. However, as dissolved polysulfides can migrate through the electrolyte and react at the metal anode, they are also related to the capacity fading and self-discharge of Li/S and Mg/S batteries. For the first time, both the electrochemical behavior as well as the solubility and stabilization of Mg polysulfides were studied. In order to reveal the influence of Li+ and Mg2+, their polysulfide solutions were systematically compared in a broad variety of solvents. At first, the polysulfide disproportionation and dissociation equilibria in solutions of “Li2S8“ and “MgS8” in DMSO, DMF, ACN, THF, DME, TEGDME, and Pyr1,4TFSI were investigated in UV/Vis spectroscopy.[2] Afterwards, the influence of additional LiTFSI and MgTFSI2, respectively, was examined and the red/ox processes of these polysulfide-containing electrolytes were studied in cyclic voltammetry experiments. In addition, quantum mechanical calculations of the stability of the individual polysulfide species were conducted. It could be shown that Mg polysulfides form similar disproportionation and dissociation equilibria as Li polysulfides. The stabilization of different polysulfide species is not only determined by the solvents’ relative dielectric permittivity and donor number, but also depends on the coordination by either Li or Mg cations in a mutual interplay with the solvent. Adding LiTFSI/MgTFSI2 intensifies the differences between the Li and Mg polysulfide solutions. As a consequence, the red/ox behavior of these solutions differ strongly. It is demonstrated that the typically high overvoltages of Mg/S cells are related to the electrochemistry of the Mg polysulfides. The achieved insights into the fundamentals of the Li/S and Mg/S cell chemistries might lead the way towards new electrolyte designs and play a key role in increasing the reversibility and lowering the overvoltages of Mg/S cells. Acknowlegdements: The authors wish to thank the BMBF for funding this work within the projects ‘ACHiLiS’ (03XP0037A) and ‘MgMeAnS’ (03XP0140). The Heinrich Böll Foundation is acknowledged for funding through a PhD scholarship.

Corrigendum to the “Volumetric properties of aqueous solution of lithium tetraborate from 283.15 to 363.15 K at 101.325 kPa” [J. Chem. Thermodyn. 120 (2018) 151–156

Abstract Errors are discovered in the authors’ computed the apparent molar volume from the reported density of aqueous solutions of lithium tetraborate based on the equation. All the apparent molar volumes presented in Table 3 of the published paper by Guo and co-workers are in error. When the composition of Li 2 B 4 O 7 is high, the difference between our calculated V ϕ values and those reported by Guo is small. However, large difference is found with low compositions of Li 2 B 4 O 7 in solutions.

Exploiting Carvone To Demonstrate Both Stereocontrol and Regiocontrol: 1,2- vs 1,4-Addition of Grignard Reagents and Organocuprates

The ability of certain organometallic reagents to react via 1,2- or 1,4-addition to an α,β-unsaturated ketone is a fundamental example of regioselectivity at the second-year undergraduate organic level. The following two experiments were designed to demonstrate this preference by exploiting carvone as an inexpensive chiral, nonracemic substrate. The first, intended for a typical undergraduate audience, makes use of phenylmagnesium bromide; the second calls for the manufacture of lithium dimethylcuprate from a stock solution of methyl lithium and copper(I) iodide and is envisioned to be carried out by upper-division students. Importantly, due to the chiral nature of carvone, these addition reactions are highly stereoselective and will provide an opportunity for students to revisit stereochemistry. Also discussed are several thoughts on assessment of student learning as well as an easy to adopt protocol that details reaction setup, aqueous workup, purification, waste management, and the analysis of products using 1H NMR spectroscopy.

Volumetric properties of aqueous solution of lithium tetraborate from 283.15 to 363.15 K at 101.325 kPa

Abstract Densities of aqueous solutions of lithium tetraborate in the (0.01 to 0.12) mol·kg−1 concentration range at a 5 K intervals from 283.15 K to 363.15 K and 101.325 kPa were measured using a precise Anton Paar Digital vibrating-tube densimeter. Apparent molar volumes are obtained on the basis of experimental density data, and then the 3D diagram of (mi, T, Vϕ) apparent molar volumes against temperature and molality were plotted. On the basis of Pitzer ion-interaction equation of the apparent molar volume model, the Pitzer single-salt parameters ( β M,X ( 0 ) v , β M,X ( 1 ) v ), β M,X ( 2 ) v and C M,X ( v ) ), and their temperature-dependence correlation F(i, p, T) = a1 + a2T + a3T2 + a4/T + a5ln(T) + a6/(T−263) + a7/(680−T) (where T is temperature in Kelvin, p is a pressure in 101.325 kPa, ai are model parameters) for Li2B4O7 are obtained, which is not reported in the literature. The deviations of the experimental and calculated values of Pitzer single-salt parameters β M,X ( 0 ) v , β M,X ( 1 ) v , β M,X ( 2 ) v and C M,X ( v ) for Li2B4O7 are all within ±0.1, and those results indicate that the single salt parameters and their relational coefficients of temperature-dependence for Li2B4O7 obtained in this work are reliable.

Gel polymer electrolytes for lithium-sulfur batteries

Gel polymer electrolytes (GPE) consisting of a solution of lithium (trifluoromethane)sulfonimide (LiTFSI) dispersed in poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(methyl methacrylate) (PMMA)/poly(N-isopropylacrylamide) (PNIPAM) matrix were prepared. Effect of montmorillonite clay mineral additives to stability and electrochemical performance was studied. GPEs exhibited up to 800 wt% electrolyte uptake, high electrochemical and thermal dimensional stability compared to Celgard separator. Li/S cells assembled with S/C composite cathode and PVDF-HFP/PMMA/PNIPAM GPE delivered initial discharge capacities of 1,300 and 850 mAh g−1 in the first and 15th cycles at 0.1 C, respectively, along with high coulombic efficiency (about 100 %) over 100 cycles. The coulombic efficiency was attributed to the suppression of shuttle effect by the gel polymer electrolyte leading to the higher sulfur utilization in the cell

Mesoporous hollow silicon spheres modified with manganese ion sieve: Preparation and its application for adsorption of lithium and rubidium ions

In this work, mesoporous hollow silicon spheres modified with 3‐aminopropyl‐ triethoxysilane (APTES) of loaded hydrogen manganese oxide lithium ion sieve (APTES/HMO‐ HS) was prepared. The structure and morphology of as‐prepared APTES/HMO‐HS were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, transmission electron microscopy and nitrogen adsorption‐desorption measurements. The Brunner‐Emmet‐Teller (BET) surface areas, pore diameters and pore volumes of APTES/HMO‐HS decreased gradually, while the Li:Mn:Si molar ratios range from 1:1:50 to 1:1:10. The obtained hierarchical porous APTES/50HMO‐HS has a high specific surface area (557.1694 m2 g‐1). The lithium and rubidium ions solutions were used to measure the adsorption performance of the APTES/HMO‐HS adsorbent. The pseudo‐first‐order and pseudo‐second‐order kinetics, Langmuir and Freundlich isotherms of APTES/HMO‐HS were investigated; suggesting that the adsorption kinetics can be described by the pseudo‐second‐order kinetic model and the adsorption isotherms well fits the Langmuir isotherm equation. The obtained results show that the prepared APTES/HMO‐HS exhibits excellent abilities to simultaneously and selectively recover Li+ and Rb+ (11.22 mg·g‐1 and 8.31 mg·g‐1) and have a promising application in the simultaneous adsorption of lithium and rubidium ions.

Dielectric Characteristics of Water and Electric Conductivity of Aqueous Electrolytes

The specific electric conductivities (ECs) of concentrated aqueous solutions of electrolytes were shown to be comparable to the limiting high-frequency (HF) EC of water. The limiting HF EC of water is determined by the ratio of the absolute dielectric constant to the dipole dielectric relaxation time. It was assumed that the specific EC of an aqueous solution cannot exceed the limiting HF EC of water. The specific ECs of the 1.0 М aqueous solutions of lithium, sodium, and potassium chlorides were calculated from the limiting HF EC of water. At elevated temperatures, the specific ECs of aqueous salts were shown to increase in direct proportion to the limiting HF EC of water.

Innovative Separation Technology for Lithium-6 Enrichment Using Electrodialysis with Lithium Ionic Superconductor

Tritium needed as a fuel for fusion reactors is produced via neutron capture by lithium-6 (6Li). However, natural Li contains only about 7.8% 6Li, and enrichment of 6Li up to 90% is required for adequate tritium breeding in fusion reactors. The mercury amalgam method is superior to some of the lithium isotope enrichment methods. In Japan, lithium isotope enrichment methods have been developed to avoid the environmental hazards of using mercury. However, the isotope separation coefficient and efficiency is too low to meet the practical need of large mass production of 6Li. Therefore, new Li isotope separation technique using a Li ionic superconductor functioning as a Li isotope separation membrane (LISM) have been developed [1]. Li ions move by electrodialysis through LISM between the cathode and the anode in lithium solutions. Because the mobility of 6Li ions is higher than that of 7Li ions, 6Li can be enriched on the cathode side of a cell. It has been reported that the difference in the mobility between 6Li and 7Li become large in ionic superconductor. The isotope effect in ionic superconductor is expected to be applicable to isotope separation membrane. In this research, we numerically investigated the ionic mobility of Li isotopes in ionic superconductor. Combing the first principle and the kinetics Monte Calro simulation, we calculate the diffusion constant of 6Li and 7Li. I show the two important effects for the difference in the mobility between isotope of Li. The first is the quantum effect, which decrease the diffusion barrier for Li ion and increase the ratio of the diffusion constant of Li isotopes. The second is the correlation effect between 6Li, 7Li and vacancy. Using Li0.29La0.57TiO3 (LLTO) as the Li ionic superconductor was prepared, and the relationship between the 6Li separation coefficient and the electrodialysis time was investigated. After electrodialysis, we obtained a maximum of 1.04 for the 6Li isotope separation coefficient. This result showed that the 6Li isotope separation coefficient of this method is the same as that of the amalgamation process using mercury (1.06). Thus, this method has the potential to be a superior 6Li enrichment method to produce 90% enriched tritium breeder for fusion reactors. Figure 1

A Cation Study on Rice Husk Biomass Pretreatment with Aqueous Hydroxides: Cellulose Solubility Does Not Correlate with Improved Enzymatic Hydrolysis

Biomass pretreatment is a key first step in converting recalcitrant lignocellulosic biomass into value-added products. Aqueous hydroxide solutions can be effective biomass pretreatment media, and the cation of the hydroxide salt can have an extremely significant effect upon the physicochemical behavior of the hydroxide solution. However, the cation effect has not been comprehensively investigated with respect to biomass pretreatment. Here, we investigated pretreatment of rice husks (from Oryza sativa) and show that the cation indeed has a significant effect upon downstream enzymatic hydrolysis of the cellulose (with cellulase). In particular, the ability of the solution to dissolve cellulose was negatively correlated with pretreatment effectiveness, as judged by the downstream glucose yield. This was observed by investigating aqueous solutions of lithium, potassium, cesium, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, and tetrahexylammonium hydroxide. Silica solubility...

A novel multifunctional soft robotic transducer made with poly (ethylene-co-methacrylic acid) ionomer metal nanocomposite

Reported is realization of a novel ionic electro-active biomimetic soft robotic polymer metal nanocomposite known as poly (ethylene-co-methacrylic acid) metal composite (called EMAMC in this paper) capable of functioning as soft robotic biomimetic actuators, energy harvesters and sensors. By soft robotic it is meant that these materials are easily deformable soft plastics like an elephant trunk. Further reported is the manufacturing methodology of the novel multi-functional electroactive polymer metal nanocomposite EMAMC. The electro-less chemical plating is performed by a chemical REDOX operation on poly (ethylene-co-methacrylic acid) or (PEMAA) ionomer with a metal. PEMAA is a commercially available ionomer commercially known as Surlyn® by DuPont and used for manufacturing golf balls. Surlyn® is a copolymer of ethylene and methacrylic acid groups and is partially neutralized with Na+ ions. To increase the ion exchange capability of Surlyn® the polymer is subjected to a chemical hydrolysis in potassium and sodium hydroxides (KOH, NaOH) and dimethyl sulfoxide (DMSO). This procedure is followed by a chemical REDOX procedure in which PEMAA is first oxidized in a metallic salt solution followed and then reduced in a lithium and sodium borohydride solutions to deposit metallic nanoparticles near boundaries and on the surfaces of hydrolyzed Surlyn®. This REDOX operation creates highly conductive electrodes on and near boundary surfaces. It is then observed that application of a low voltage across the EMAMC causes it to deform softly (actuation mode) with a significant force density and soft bending and deforming the EMAMC will generate electricity (energy harvesting and sensing modes). The preliminary results of actuation and sensing of the EMAMC are reported in this paper.

The synthesis of Li(Co Mn Ni)O2 cathode material from spent-Li ion batteries and the proof of its functionality in aqueous lithium and sodium electrolytic solutions

Abstract Several spent Li-ion batteries were manually dismantled and their components were uncurled and separated. The chemical composition of each battery's component was determined by atomic absorption spectroscopy. Among several ways to separate cathode material from the collector, the alkali dissolution treatment was selected as the most effective one. After both complete separation and acid leaching steps, the co-precipitation method, followed by a thermal treatment (700 °C or 850 °C), was used to resynthesize cathode material LiCo0.415Mn0.435Ni0.15O2. Its structure and morphology were characterized by XRD, Raman spectroscopy and SEM-EDS methods. The electrochemical behavior of recycled cathode materials was examined by cyclic voltammetry and chronopotentiometry in both LiNO3 and NaNO3 aqueous solutions. High sodium storage capacity, amounting to 93 mAh g−1, was measured galvanostatically at a relatively high current of ∼100 mA g−1. Initial lithium intercalation capacity of ∼64 mAh g−1, was determined potentiodynamically at very high scan rate of 20 mV s−1 (∼40 C). Somewhat lower initial capacity of ∼30 mAh g−1, but much lower capacity fade on cycling, was found for sodium intercalation at the same scan rate. The differences in the Li and Na charge storage capability were explained in terms of ion rearrangement during charging/discharging processes.

Influence of cations in lithium and magnesium polysulphide solutions: dependence of the solvent chemistry.

In order to gain a deeper understanding of Li and Mg polysulphides in Li/S and Mg/S batteries, respectively, this work investigates the impact of the two different cations as well as the influence of the electrolyte solvents' relative dielectric permittivity and Gutmann's donor number on the solubility and relative stability of different Li and Mg polysulphide species. Therefore, the disproportionation and dissociation equilibria of chemically prepared "Li2S8" and "MgS8" solutions in DMSO, DMF, ACN, THF, DME, TEGDME, and Pyr14TFSI are characterized by UV/Vis spectroscopy. Varying the cation and the solvent reveals their mutual interplay in stabilizing different polysulphide species. To our knowledge, this is the first time that chemically synthesized Mg polysulphides in solutions are studied. The results of this work provide essential knowledge for further development of the economically, ecologically, and also in terms of energy density and safety, attractive Mg/S batteries.

Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces

The use of high-concentration salts in electrolyte solutions of lithium–sulfur (Li–S) batteries has been shown to be beneficial for mitigating some effects such as polysulfide shuttle and dendrite growth at the Li metal anode. Such complex solutions have structural-, dynamical-, and reactivity-associated issues that need to be analyzed for a better understanding of the reasons behind such beneficial effects. A passivation interfacial layer known as solid–electrolyte interphase (SEI) is generated during battery cycling as a result of electron transfer from the metal anode causing electrolyte decomposition. Here, using density functional theory and ab initio molecular dynamics simulations, we investigate the salt decomposition, solvation effects, interactions among intermediate products and other species, and potential components of the SEI layer as a function of chemical nature and concentration of the salt for lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI)...

Estimation of differential heat of dilution for aqueous lithium (bromide, iodide, nitrate, chloride) solution and aqueous (lithium, potassium, sodium) nitrate solution used in absorption cooling systems

The differential heat of dilution data are estimated theoretically using Duhring's diagrams for water/LiBr, water/(LiBr + LiI + LiNO3 + LiCl) with mass compositions in salts of 60.16%, 9.55%, 18.54% and 11.75%, respectively, and water/(LiNO3 + KNO3 + NaNO3) with mass compositions in salts of 53%, 28% and 19%, respectively, as these can be potentially utilized as working fluids in absorption cooling systems. The differential heat of dilution data obtained were correlated with simple polynomial equations for the three working fluids as a function of the solution concentration and temperature. The results showed that the differential heat of dilution of the non-conventional working fluid mixtures is lower than that of water/LiBr at typical operating temperature and concentration of interest in absorption cooling cycles employing these working fluid mixtures. The correlations developed could be useful in predicting the differential heat of dilution value while performing heat and mass transfer analyses of these potential non-conventional working fluid mixtures in absorption cooling systems.

Carbon-based electrochemical capacitors with acetate aqueous electrolytes

This paper reports on the performance of the supercapacitor operating in aqueous acetic acid salts. Lithium, sodium and magnesium acetate aqueous solutions at various concentrations have been selected as electrolytes. Maximum operational voltage and the overall capacitor performance have been determined by several electrochemical techniques. Floating and galvanostatic charge/discharge tests proved the promising performance at high voltages (1.5V); the capacitance values have been retained at more than 80% of initial value for all tested electrolytes. Additionally, due to the the ability to operate at high voltages, the maximum energy obtained in the system with 0.5molL−1 CH3COONa is more than two times higher than with 6molL−1 KOH, i.e., conventional aqueous capacitor. Taking into account a mild character of the electrolytes used, a novel concept of eco-friendly energy storage device has been proposed.

Ionic liquid incorporated nanocomposite polymer electrolytes for rechargeable lithium ion battery: A way to achieve improved electrochemical and interfacial properties

An ionic liquid incorporated nanocomposite electrolytes are prepared using solution cast technique by immobilizing a solution of lithium N,N-bis(trifluoromethanesulfonyl)imide (LiTFSI) in N-ethyl-N-methylimidazolium - bis(trifluoromethanesulfonyl) imide (EMImTFSI) ionic liquid (IL) with added mixtures of organic solvent and nanofiller such as acetonitrile and nanochitosan (32nm) into a poly(ethylene oxide) (PEO) matrix. The achieved extreme ionic conductivity of ionic liquid based electrolyte is in the range of 10⿿2Scm⿿1 which is one order higher than that of (PEO)8LiTFSI-10wt% NC system. Cyclic voltammetry and linear sweep voltammetry (LSV) analyses indicates that the prepared electrolytes possesses an excellent electrochemical stability of 3.9V. These unique properties allow the effective use of these membranes as active separators for the development of advanced lithium ion batteries.

Solvation environment of lithium ion in a LiBF4–propylene carbonate system in the presence of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid studied by NMR and quantum chemical modeling

Solutions of lithium and 1-ethyl-3-methylimidazolium tetrafluoroborates ([emim][BF4]) in propylene carbonate (PC) were studied by the high-resolution NMR method on 1H, 7Li, 11B, 13C, and 19F nuclei. The degree of solvation of lithium ions was determined by measuring selfdiffusion coefficients by pulse-field-gradient spin echo NMR method on 1H, 7Li, and 19F nuclei. The hydrodynamic radii of solvated Li+ cations were estimated by the Stokes–Einstein equation. The model structures of the solvation complexes of Li+ ion with propylene carbonate molecules and BF 4 – anion and their associates with ionic liquid components were calculated in terms of the density function theory. The calculated values of the chemical shifts were compared with the experimental data. PC molecules were predominantly bound to the Li+ cation, while LiBF4–[emim][BF4]–PC (1: 4: 4) electrolyte had a maximum conductivity of 9.5 mS cm–1 at 24 °С compared to the compositions of a lower content of the solvent.

Electrochemical Profile of LiTi2(PO4)3 and NaTi2(PO4)3 in Lithium, Sodium or Mixed Ion Aqueous Solutions

Carbon-coated LiTi2(PO4)3 and NaTi2(PO4)3 were prepared using the sol-gel method, followed by solid-state reaction and thermal decomposition vapor deposition process. The electrochemical profile of both compounds were examined in three different aqueous electrolytes, including 1 M Li2SO4, 1 M Na2SO4 and 1 M Li2SO4/Na2SO4 mixed solutions (1:1 in the volume ratio). Both Li and Na ions can successfully inserted into these NASCION materials, and the two materials deliver a similar higher discharge potential in the Li2SO4 solution (−0.76 V vs. Ag/AgCl) compared to that in the Na2SO4 solution (−0.8 V vs. Ag/AgCl) after several charge/discharge cycles. The XRD analysis demonstrate that LiTi2(PO4)3 is converted to NaTi2(PO4)3 in the Na2SO4 and mixed solutions, and NaTi2(PO4)3 was transformed to LiTi2(PO4)3 in the Li2SO4 solution after cycling. It suggests that the Li or Na ions in the M1 sites of the NASCION materials are replaced by the ions from the electrolyte, but Na ions prefer to occupy the M1 sites compared with Li ions.

Liquid Membrane Permeation with Supported Liquid Membranes and their Application in Li-ion Battery Recycling

A study of liquid membrane permeation with supported flat sheet membranes was performed. The goal of the project was to improve the stability and accuracy of supported liquid membranes (SLM) by avoiding short circuiting of phases with technical measures. Mass transfer and stability tests were carried out with the test system Zn2+|HDEHPA|H+. The effect of operation conditions on mass transfer and accumulation of Zn2+ in the stripping phase was investigated. A process for the recycling of Li-ion batteries including two SLM separation stages was developed. Experimental findings confirmed the feasibility of this process, yielding high purity streams of aqueous copper, cobalt, and lithium solutions.

Li+ adsorption/desorption properties of lithium ion-sieves in aqueous solution and recovery of lithium from borogypsum

This study presents the recovery of lithium from borogypsum by lithium ion-sieves known as selective adsorbents. In the study two types of ion-sieves were used. One was λ-MnO2 which was obtained by the treatment of LiMn2O4 with acid and the other was prepared via the acid treatment of LiNi0.5Mn1.5O4 which occurred by the substitution some of manganese with nickel. Besides the lithium adsorption and desorption capacities, manganese and nickel dissolution ratios from the spinel powders were also studied. Optimum adsorption and desorption conditions were determined in the LiOH and HCl solutions. XRD and SEM analyses showed that substitution of manganese with nickel and treatment of spinel powders with acid did not destroy the spinel structure and morphology. Because of the cell-contraction, nickel-substituted spinel did not show any satisfying Li+ extraction and adsorption properties.