Competition between Li+ and Mg2+ for red blood cell membrane phospholipids: A 31P, 7Li, and 6Li nuclear magnetic resonance study

The mode of action of the lithium ion (Li⁺) in the treatment of manic depression or bipolar illness is still under investigation, although this inorganic drug has been in clinical use for 50 yr. Several research reports have provided evidence for Li⁺/Mg²⁺ competition in biomolecules. We carried out this study to characterize the interactions of Li⁺ and Mg²⁺ with red blood cell (RBC) membrane components to see whether Li⁺/Mg²⁺ competition occurs. ³¹P nuclear magnetic resonance chemical shift measurements of the phospholipids extracted from the RBC membranes indicated that the anionic phospholipids, phosphatidylserine and phosphatidylinositol, bind Li⁺ and Mg²⁺ most strongly. From ⁶Li relaxation measurements, the Li⁺ binding constant to the phospholipid extract was found to be 45±5M⁻¹. Thus, these studies showed that the phospholipids play a major role in metal ion binding. ⁷Li spin-lattice relaxation measurements conducted on unsealed and cytoskeleton-depleted RBC membrane in the presence of magnesium indicated that the removal of the cytoskeleton increases lithium binding to the more exposed anionic phospholipids (357±24 M⁻¹) when compared to lithium binding in the unsealed RBC membrane (221±21 M⁻¹). Therefore, it can be seen that the cytoskeleton does not play a major role in Li⁺ binding or in Li⁺/Mg²⁺ competition.     

Electrochemical Recovery of Lithium Ions in the Aqueous Phase

Abstract

The electrochemical insertion of lithium ions into a Pt/λ-MnO₂ electrode was investigated in various metal chloride solutions. The Li⁺ insertion occurred effectively in LiCl solutions with higher concentration than 10 mmol/dm³, but it could hardly occur in a 0.1 mmol/dm³ LiCl solution. Alkaline earth metal ions showed a stronger inhibition effect against the Li⁺ insertion into the Pt/λ-MnO₂ electrode than alkali metal ions. However, since only Li⁺ ions were taken up from a mixed solution of lithium and alkaline earth metal chlorides, a high selectivity of the electrode for lithium ions was shown.

It was possible to recover lithium ions from geothermal water by this electrochemical method using the Pt/λ-MnO₂ electrode; the lithium uptake was 11 mg/g-MnO₂.     

Amorphous TiO2-Derived Large-Capacity Lithium Ion Sieve for Lithium Recovery

The lithium titanium oxide ion sieve with good structural stability and high adsorption capacity is generally considered to be a promising adsorbent for lithium recovery. Herein, the lithium ion sieve precursor Li₂TiO₃ was prepared based on amorphous TiO₂, and then Li⁺ was acid-eluted to obtain the lithium adsorbent H₂TiO₃, denoted as HTO-Am. The structure and adsorption properties of HTO-Am were investigated, and the results demonstrated that the HTO-Am prepared at the optimum temperature had excellent adsorption properties for Li⁺. The adsorption process follows pseudo-second-order kinetic and Langmuir isotherm equations, indicating that lithium is adsorbed chemically and monolayer on HTO-Am. HTO-Am ion sieves were prepared successfully for the first time and exhibited high selectivity, favorable adsorption rate, and cycle performance for Li⁺.     

Investigating the Role of GABA in Neural Development and Disease Using Mice Lacking GAD67 or VGAT Genes

Normal development and function of the central nervous system involves a balance between excitatory and inhibitory neurotransmission. Activity of both excitatory and inhibitory neurons is modulated by inhibitory signalling of the GABAergic and glycinergic systems. Mechanisms that regulate formation, maturation, refinement, and maintenance of inhibitory synapses are established in early life. Deviations from ideal excitatory and inhibitory balance, such as down-regulated inhibition, are linked with many neurological diseases, including epilepsy, schizophrenia, anxiety, and autism spectrum disorders. In the mammalian forebrain, GABA is the primary inhibitory neurotransmitter, binding to GABA receptors, opening chloride channels and hyperpolarizing the cell. We review the involvement of down-regulated inhibitory signalling in neurological disorders, possible mechanisms for disease progression, and targets for therapeutic intervention. We conclude that transgenic models of disrupted inhibitory signalling—in GAD67^+/− and VGAT^−/− mice—are useful for investigating the effects of down-regulated inhibitory signalling in a range of neurological diseases.     

Crystal structure investigation of spinel-type LiAlON with multiple atomic disorders

Spinel-type lithium aluminum oxynitride (LiAlON) contains atomic disorders at every crystallographic position, including vacancies, cation, and anion disorders. In this work, the crystal structure of spinel-type LiAlON with multiple atomic disorders was systematically studied by first-principles calculation, solid-state NMR, and the Rietveld crystal structure refinement. The theoretical simulations demonstrate that the Li⁺ occupies octahedral positions and prefers to be far away from the N³⁻ and cation vacancies in the crystal structure of LiAlON. A spinel-type LiAlON compound with chemical formula of Li_0.06Al_2.72O_3.77N_0.23 was prepared by solid-state reaction. The local structure of Li⁺ and Al³⁺ was probed by ⁷Li and ²⁷Al solid-state NMR technology. Combined with theoretical calculations and solid-state NMR, the crystal structure of Li_0.06Al_2.72O_3.77N_0.23 was fully resolved by the Rietveld refinement. This work provides a deep understanding on the disordered crystal structure of the spinel-type LiAlON solid solution.     

Modification of phenolic resins containing crown ether units

Summary Phenolic resins containing 13-crown-4 and 9-crown-3 units (1) were modified by coupling and nitration in heterogeneous phase. The chromogenic resins extract Li⁺ selectively and efficiently, and no extractions of Na⁺ were found. The extractions were carried out with aqueous solutions of lithium and aqueous solutions of sodium chloride at pH=7 and 11. Finally, re-extraction analysis of lithium in methanol and water were made. Resins release partially the cation. Major re-extraction was obtained with methanol.     

Adsorption behavior of Li+ onto nano-lithium ion sieve from hybrid magnesium/lithium manganese oxide

Magnesium (II) doped spinel lithium manganese oxide (LMS) was synthesized by soft chemical method and nanosized ion sieve manganese oxide (HMS) was prepared by extracting lithium and magnesium from LMS. The characteristics of HMS were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, surface areas and determination of pH at the point of zero charge. Experiments were performed to study the effects of pH, adsorbent dose, contact time and Li⁺ concentration. The competitive model was used to describe the competition between Li⁺–H⁺ and the applicability of different kinetic models was evaluated. The results showed that the pH at the point of zero charge of HMS was about 7.8. The recycle of HMS explained that it could be used as Li⁺ adsorbent with topotactical extraction of lithium. Under optimized batch conditions up to 99.2% Li⁺ could be recovered from solution within 24 h. The adsorption process followed the pseudo-second-order model and followed an intraparticle diffusion model at the beginning.     

In situ FTIR spectra at the Cu electrode/propylene carbonate solution interface

In situ Fourier transform infrared spectroscopy (FTIR) spectra measurements were obtained for a Cu electrode/solution of lithium perchlorate in propylene carbonate (PC). The dependence of potential on the concentration of PC in the vicinity of the electrode was investigated. The bands due to free PC and PC solvated to lithium ions in the solution were distinguished by the single reflection attenuated total reflection (ATR) spectra. In the FTIR spectra, the reversible change in the concentration of free PC and solvated PC in the diffuse double layer was observed to be accompanied by a change in potential. As the potential decreased, the free PC concentration increased, while the concentration of the PC solvated to lithium ions decreased. Thus, it can be concluded that the equilibrium shifts from Li⁺(PC)₄ to Li⁺(PC)₃ + PC as the potential decreases. Furthermore, Li⁺(PC)₃ orientates itself so that it is parallel to the electrode surface.     

Li1.6Mn1.6O4/PVDF多孔膜的制备及提锂性能

自制锂离子筛前驱体Li_1.6Mn_1.6O₄，并将Li_1.6Mn_1.6O₄粒子与高分子树脂PVDF杂化制膜，研究了膜经稀盐酸抽锂后对锂的吸附性能以及多次吸附与脱附性能等。结果表明，膜M-10-55[Li]采用0.5 mol·L^-1 HCl溶液抽锂约2 h锂的脱出基本达到平衡，Li⁺的洗脱率在95%左右，锰的溶损率为3.5%左右。抽锂后得M-10-55[H]对富锂溶液中锂的吸附约12 h达平衡，对锂的吸附容量较高为41 mg·g^-1，在第5次吸附时对锂的提取量为35 mg·g^-1左右。相比于Na⁺、K⁺、Mg²⁺、Ca²⁺，该膜对Li⁺表现出较好的选择性，对于从海水、盐湖卤水等液态锂资源中提取锂有很大的开发潜力。     

Extraction relationship of Li+ and H+ using tributyl phosphate in the presence of Fe(III)

ABSTRACT

During the extraction of lithium from high Mg-containing salt lake brines by tributyl phosphate (TBP) in the presence of Fe(III), H⁺ is used to stabilize Fe(III). However, the distribution ratio of H⁺ (D_H) is 4–6 times higher than that of Li⁺ (D_Li), which affects the extraction of Li⁺ significantly. In this study, the competition mechanism between H⁺ and Li⁺ was investigated by spectral analysis and thermodynamic equilibrium. The extracted species are determined as HFeCl₄ · 2TBP and LiFeCl₄ · 2TBP for H⁺ and Li⁺, respectively. The apparent equilibrium constants are K_H = 799.8 and K_Li = 120.6, respectively. Both equilibrium constants and the distribution ratios for H⁺ and Li⁺ extraction show that extraction of H⁺ is stronger than Li⁺.     

Highly selective,regenerated ion-sieve microfiltration porous membrane for targeted separation of Li<Superscript>+</Superscript>

A novel adsorbent lithium ion-sieve membrane (LISM) toward Li⁺ was successfully prepared by the phase inversion technique using synthesized lithium ion-sieve ultrafine powder as the precursor, poly(vinylidene fluoride) (PVDF) as a binder, N,N-dimethylacetamide (DMAc) as the solvent. The key design for the synthesis of LISM is the formation of lithium ion-sieve dropping with PVDF powder to obtain a highly selective adsorbent. The prepared LISM have been characterized. The X-ray diffraction illustrated that the synthesized lithium ion-sieve were purity phase cubic spinel structure, the scanning electron microscopy shown that the LISM with a poriferous surface morphology and lithium ion-sieve equably dispersed on the surface of the membrane. The membrane flux (9.7 mL cm^?1 min^?1) suggested that the LISM achieved high hydrophily and stability. The maximum adsorption capacity is 27.8 mg g^?1 in a high adsorption rate towards Li⁺ within 60 min. In addition, the LISM has excellent adsorption selectivity, since the separation factor α is 4.76 with respect to Mg²⁺. Overall results revealed that the LISM as a good candidate for Li⁺ separation and concentration from salt lake brine with a relatively high value of Mg²⁺/Li⁺ ratio.     

Effect of lithium butoxide additives on the anionic propagation of polystyryllithium in ethereal solvents

The addition of tertiary butoxide lithium (t-BuOLi) was found to slow down the anionic propagation of polystyryllithium (PStLi) in tetrahydropyran (THP), whereas, the addition of normal butoxide lithium (n-BuOLi) increases the rate over the investigated ranges of PStLi concentrations. Both lithium butoxides, which are tetrameric in ethereal solvents, also increase the conductance of PStLi in THP solution much more than expected on the basis of the separate conductances of PStLi and the lithium alkoxides and the increase is more important in the case of the addition of n-BuOLi than in that of t-BuOLi.These phenomena are fully accounted for by a similar mechanism as that invoked to explain the influence of the addition of lithium chloride (LiCl), which contrasts at first sight with the lithium alkoxides by displaying both a retarding and an accelerating effect at the lower and the higher concentrations respectively of the investigated PStLi concentration domain.This common cause of the observed phenomena consists of the dissociation of the dimers of LiCl or the tetramers of the lithium alkoxides into the free Li⁺-ion and the multiple anions (ClLiCl⁻ in the case of LiCl and (BuOLi)₃BuO⁻ in the case of the lithium alkoxides) but also of the often overlooked Li⁺-ion scavenging reaction by the LiCl dimers or the lithium alkoxide tetramers producing multiple cations. The first reaction providing Li⁺-ions represses the ionic dissociation of PStLi by a common ion effect reducing thereby the amount of free PSt⁻-anions which are the main contributors to the rate of propagation and resulting therefore, in retardation. The second one scavenging Li⁺-ions reduces the concentrations of free Li⁺-ions and increases therefore, the concentration of reactive free polystyryl anions and as a consequence accelerates the propagation reaction.The concentration of PStLi at which a crossover occurs from retardation to acceleration lies for the addition of LiCl in the investigated range of PStLi concentrations. For the addition of t-BuOLi calculations show that this crossover concentrations lies above the highest investigated PStLi concentration, whereas, for the addition of n-BuOLi it lies below the lowest investigated PStLi concentration giving the impression that t-BuOLi only retards the propagation and that n-BuOLi only accelerates but in actual fact the same mechanism is operating in all three cases.     

On the difference in cycling behaviors of lithium-ion battery cell between the ethylene carbonate- and propylene carbonate-based electrolytes

Density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations have been performed to gain insight into the difference in cycling behaviors between the ethylene carbonate (EC)-based and the propylene carbonate (PC)-based electrolytes in lithium-ion battery cells. DFT calculations of the lithium solvation, Li⁺(S)_i (S = EC or PC; i = 1–4) with and without the presence of the counter anion showed that the desolvation energy to remove one solvent molecule from the first solvation shell of the lithium ion was significantly reduced by as much as 70 kcal mol⁻¹ (293.08 kJ mol⁻¹) in the presence of the counter anion, suggesting the lithium ion is more likely to be desolvated at high salt concentrations. The thermodynamic stability of the ternary graphite intercalation compounds, Li⁺(S)_iC₇₂, in which Li⁺(S)_i was inserted into a graphite cell, was also examined by DFT calculations. The results suggested that Li⁺(EC)_iC₇₂ was more stable than Li⁺(PC)_iC₇₂ for a given i. Furthermore, some of Li⁺(PC)_iC₇₂ were found to be energetically unfavorable, while all of Li⁺(EC)_i=1–4C₇₂ were stable, relative to their corresponding Li⁺(S)_i in the bulk electrolyte. In addition, the interlayer distances of Li⁺(PC)_iC₇₂ were more than 0.1 nm longer than those of Li⁺(EC)_iC₇₂. MD simulations were also carried out to examine the solvation structures at a high salt concentration of LiPF₆: 2.45 mol kg⁻¹. The results showed that the solvation structure was significantly interrupted by the counter anions, having a smaller solvation number than that at a lower salt concentration (0.83 mol kg⁻¹). We propose that at high salt concentrations, the lithium desolvation may be facilitated due to the increased contact ion pairs so as to form a stable ternary GIC with less solvent molecules without destruction of graphite particles, followed by solid–electrolyte-interface film formation reactions. The results from both DFT calculations and MD simulations are consistent with the recent experimental observations.     

Impedance study of protecting film formation on lithium and lithiated graphite induced by bis(fluorosulfonyl) imide anion

The process of Li⁺ reduction from room temperature ionic liquids consisting of N-methyl-N-propylpyrrolidinium cation (MPPyr⁺) and bis(fluorosulfonyl) imide (FSI⁻) or bis(trifluoromethanesulfonyl) imide (TFSI⁻) anions was studied with the use of impedance spectroscopy. Reduction was carried out on both metallic lithium (Li) and graphite (G) electrodes. It has been found that the FSI anion in high amounts is able to form a protective film on both graphite and metallic lithium. The Li⁺/Li couple should rather be represented by a Li⁺/SEI/Li system. The SEI structure depends on the manner of its formation (chemical or electrochemical) and is not stable with time. The rate constant for the Li⁺ + e⁻ → Li process at the Li/SEI/Li⁺ (in MPPyrFSI) interface is k_o = 4.2 × 10⁻⁵ cm/s. In the case of carbon electrodes (G/SEI/Li⁺ interface), lithium diffusion in solid graphite is the rate determining step, reducing current by ca. two orders of magnitude, from ca. 10⁻⁴ A/cm², characteristic of the Li/SEI/Li⁺ electrode, to ca. 10⁻⁶ A/cm².     

Enhancement in Li+/Mg2+ separation from salt lake brine with PDA–PEI composite nanofiltration membrane

Extraction of lithium from high Mg²⁺/Li⁺ ratio salt lake brine with the nanofiltration (NF) membrane is significantly challenging. Interfacial polymerization was utilized for the facile modification of NF membranes with polydopamine (PDA) and polyethylenimine (PEI) to enhance lithium separation efficiency. Comparing permeability and salts rejection (Li⁺ and Mg²⁺) of three NF membranes before and after PDA/PEI deposition, it was observed that separation efficiency was not only dependent on steric hindrance but also affected by Donnan exclusion mechanism. In the case of NF270 membrane after facile polymerization, due to small pore size distribution and low charge density confirmed by zeta potential measurements, Li⁺ permeability was reached about 95% at a flux of 21.33 L·m⁻²·h⁻¹. Although with the DK membrane, separation factor SF_Li/Mg was also increased up to 60 after modification, the pore narrowing effect significantly decreased lithium permeability and flux. Experimental results showed that facile modification not only enhanced stability and hydrophilicity but also reduced the high Mg²⁺/Li⁺ ratio from 30 to 4.1 in single-stage separation.     

Synthesis of hollandite-type LixMnO2 by Li ion-exchange in molten salt and lithium insertion characteristics

The Li⁺ ion-exchange reaction of K⁺-type α-K_0.14MnO_1.93·nH₂O containing different amounts of water molecules (n = 0-0.15) with a large (2 × 2) tunnel structure has been investigated in a LiNO₃-LiCl molten salt at 300 °C. The Li⁺ ion-exchanged products were examined by chemical analysis, X-ray diffraction, and transmission electron microscopy measurements. The K⁺ ions and the hydrogens of the water molecules in the (2 × 2) tunnels of α-MnO₂ were exchanged by Li⁺ ions in the molten salt, resulting in the Li⁺-type α-MnO₂ containing different amounts of Li⁺ ions and lithium oxide (Li₂O) in the (2 × 2) tunnels with maintaining the original hollandite structure.The electrochemical properties and structural variation with initial discharge and charge-discharge cycling of the Li⁺ ion-exchanged α-MnO₂ samples have been investigated as insertion compounds in the search for new cathode materials for rechargeable lithium batteries. The Li⁺ ion-exchanged α-MnO₂ samples provided higher capacities and higher Li⁺ ion diffusivity than the parent K⁺-type materials on initial discharge and charge-discharge cyclings, probably due to the structural stabilization with the existence of Li₂O in the (2 × 2) tunnels.     

Li6V10O28, a novel cathode material for Li-ion battery

A novel cathode material, lithium decavanadate Li₆V₁₀O₂₈ with a large tunnel within the framework structure for lithium ion battery has been prepared by hydrothermal synthesis and annealing dehydration treatment. The structure and electrochemical properties of the sample have been investigated. The novel material shows good reversibility for Li⁺ insertion/extraction and long cycle life. High discharge capacity (132 mAh/g) is obtained at 0.2 mA/cm² discharge current and potential range between 2.0 and 4.2 V versus Li⁺/Li. AC impedance of the Li/Li₆V₁₀O₂₈ cell reveals that the cathode process is controlled mainly by Li⁺ diffusion in the active material. The novel material would be a promising cathode material for Li-ion batteries.     

Synergistic interplay between D2EHPA and TBP towards the extraction of lithium using hollow fiber supported liquid membrane

Extraction of lithium (Li⁺) from synthetically prepared sea bittern using di-2-ethyl hexyl phosphoric acid (D2EHPA) and tri-n-butyl phosphate (TBP) as organic extractants has been studied. The equilibrium studies conducted show synergistic effect between D2EHPA and TBP. The equilibrium constant values for Li⁺, Na⁺ and K⁺ ions were found to be 95.4 × 10^?5 m³/kmol, 4.6 × 10^?5 m³/kmol and 3.69 × 10^?5 m³/kmol, respectively. Hollow fiber supported liquid membrane (SLM) experiments with low concentrations of Li⁺, Na⁺ and K⁺ ions in feed phase showed high flux for Li⁺ ions. However, at significantly high concentrations of Na⁺ and K⁺ in the feed phase, the flux of Li⁺ ions reduced. The model predictions were found to be in good agreement with the experimental data.     

Hybrid Cation Exchange Membranes with Lithium Ion‐Sieves for Highly Enhanced Li+ Permeation and Permselectivity

Cation exchange membranes (CEMs) hold promise for efficient and environment‐friendly lithium extraction from salt‐lake brine. However, development and practical application of CEMs are significantly hindered by the low Li⁺ permeation and permselectivity. Herein, novel hybrid CEMs are developed by dispersing lithium ion‐sieves (LMO) into sulfonated poly(ether ether ketone) matrix. Two kinds of LMOs are synthesized including acidified LMO (HMO) and its sulfonation compound (HMO‐S). The physicochemical property and separation performance of hybrid membranes are systematically investigated. The uniformly dispersed HMO and HMO‐S enhance the thermal, mechanical stability, and swelling resistance of hybrid membranes. Furthermore, these fillers obviously reduce the area resistance from 8.0 to less than 6.0 Ω cm^?2. Importantly, the unique Li⁺ transfer channels in HMO/HMO‐S efficiently elevate the Li⁺ permeation by up to 66%. While the “ion‐sieve effect” of the channels weakens the migration of Mg²⁺ and K⁺, thus notably rising Li⁺/Mg²⁺ and Li⁺/K⁺ permselectivities by ≈5 times, which is difficult to realize with conventional fillers. Comparing with HMO, HMO‐S shows higher improvement for permselectivity because of the reduced area resistance of the resultant hybrid membrane. This study paves a way to design and development of selective Li⁺ exchange membranes for transport and separation applications.     

Solid-state nuclear magnetic resonance investigation of cation siting in LiNaLSX zeolites

The location of Li⁺ and Na⁺ cations in a series of dehydrated low-silica LiNaX zeolites (LiNaLSX, framework Si/Al ratio=1.0) were characterized by ⁷Li and ²³Na magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. Depending on the Li⁺ content, up to three lines were observed in the ⁷Li MAS NMR spectra attributed to Li⁺ cations on SI′, SII and SIII sites. The ²³Na MAS NMR spectra of the pure sodium form NaLSX and of LiNaLSX samples with low Li⁺ contents contain up to five lines belong to Na⁺ cations located on SI, SI′, SII, and two different SIII′ sites. LiNaLSX zeolites containing more than 40% of Li⁺ show only a single narrow line in the ²³Na MAS NMR spectra attributed to mobile sodium cations. The populations of the different cation sites were determined from the relative line intensities of the MAS NMR spectra. Below about 70% Li⁺ exchange, lithium cations are located only on sites SI′ and SII. Between 70% and 100% Li⁺ content these sites are fully occupied by Li⁺, and the population of site SIII by Li⁺ increases. It was found that the nitrogen-adsorption capacity correlates well with the occupation of Li⁺ at site SIII.