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Summary Lithium metal electrodeposits in the form of irregular morphological features, loosely termed dendrites, on planar anode substrates. The deposits may lead to rapid battery failure and safety concerns. Due to the highly reducing nature of Li (−3.04 V versus standard hydrogen electrode [SHE]), a solid electrolyte interphase (SEI) inevitably forms at the electrode/electrolyte interface, which regulates the subsequent electrodeposition of Li. Rational design of the chemical, mechanical, and ion transport properties of SEI plays an important role in determining the morphology of electrodeposited metals. We report on using initiated chemical vapor deposition (iCVD) to create ultrathin conformal zwitterionic polymeric interphases with precise thicknesses in the range of 10–500 nm. It was found that zwitterionic moieties are able to tune the solvation environment of the lithium cation at the electrode/electrolyte interface, enabling compact, planar deposition of the lithium metal. These findings provide new directions for designing ionic polymeric interphases for metal anodes.

Metal–organic frameworks (MOFs) have emerged as an important, yet highly challenging class of electrochemical energy storage materials. The chemical principles for electroactive MOFs remain, however, poorly explored because precise chemical and structural control is mandatory. For instance, no anionic MOF with a lithium cation reservoir and reversible redox (like a conventional Li-ion cathode) has been synthesized to date. Herein, we report on electrically conducting Li-ion MOF cathodes with the generic formula Li2-M-DOBDC (wherein M = Mg2+ or Mn2+; DOBDC4– = 2,5-dioxido-1,4-benzenedicarboxylate), by rational control of the ligand to transition metal stoichiometry and secondary building unit (SBU) topology in the archetypal CPO-27. The accurate chemical and structural changes not only enable reversible redox but also induce a million-fold electrical conductivity increase by virtue of efficient electronic self-exchange facilitated by mix-in redox: 10–7 S/cm for Li2-Mn-DOBDC vs 10–13 S/cm for the isoreticular H2-Mn-DOBDC and Li2-Mg-DOBDC, or the Mn-CPO-27 compositional analogues. This particular SBU topology also considerably augments the redox potential of the DOBDC4– linker (from 2.4 V up to 3.2 V, vs Li+/Li0), a highly practical feature for Li-ion battery assembly and energy evaluation. As a particular cathode material, Li2-Mn-DOBDC displays an average discharge potential of 3.2 V vs Li+/Li0, demonstrates excellent capacity retention over 100 cycles, while also handling fast cycling rates, inherent to the intrinsic electronic conductivity. The Li2-M-DOBDC material validates the concept of reversible redox activity and electronic conductivity in MOFs by accommodating the ligand’s noncoordinating redox center through composition and SBU design.

Lithium cations were observed to accelerate the hydrolysis of esters with hydroxides (KOH, NaOH, LiOH) in a water/tetrahydrofuran (THF) two-phase system. Yields in the hydrolysis of substituted benzoates and aliphatic esters using the various hydroxides were compared, and the effects of the addition of lithium salt were examined. Moreover, it was presumed that a certain amount of LiOH was dissolved in THF by the coordination of THF with lithium cation and hydrolyzed esters even in the THF layer, as in the reaction by a phase-transfer catalyst.

Lithium-sulfur (Li-S) batteries are considered to be one of the next-generation battery candidates and have been widely studied. Despite the obvious advantages of Li-S batteries, there are still many serious problems with sulfur electrode: The active material sulfur (S) and the final product lithium sulfide (Li2S) are both insulators, and the electronic conductivity is poor, so that a large amount of conductive agent must be added to the sulfur electrode; the large difference in density between S and Li2S makes the electrode undergo a huge volume change (about 80%) during the charge and discharge process, which easily leads to the collapse of the sulfur electrode structure, which leads to the degradation of the Li-S batteries performance; the lithium polysulfide produced during charge and discharge has extremely high solubility in ether electrolytes, resulting in the “shuttle effect”. Especially, the “shuttle effect” of lithium polysulfide has caused problems such as poor battery cycle performance, rapid capacity decay and overcharge, which severely restricted the further development and commercial application of Li-S batteries. As a key component of Li-S batteries, electrolyte not only plays a role in transmitting lithium cation (Li+) and conducting internal circuits, but also one of the main factors that determine the overall performance of the battery capacity and cycle stability. Lithium nitrate (LiNO3) has received widespread attention as an electrolyte additive for Li-S batteries, and its mechanism of action has also been studied in depth. However, this article provides a new understanding of the mechanism of LiNO3 additives through deep study and new experimental schemes. In this experimental scheme, the Li metal anode recycled by electrolyte containing LiNO3 additive and fresh sulfur electrode was used to reassemble the battery with the electrolyte without the LiNO3 additive; the sulfur electrode recycled by electrolyte containing LiNO3 additive and fresh Li metal anod were used to reassemble the battery with the electrolyte without the LiNO3 additive; both batteries have serious overcharging during the charging process, and the shuttle of polysulfide anions occurs. This shows that the mechanism of LiNO3 inhibiting the “shuttle effect” is not just to form SEI film. Through the ion migration number test, it is found that after adding LiNO3 additive, the migration number of Li+ increases, resulting in a significant decrease in the migration of polysulfide anions. It can be concluded that another effect of adding LiNO3 additives is to increase the migration number of Li+, thereby reducing the migration number of anions and effectively inhibiting the “shuttle effect”. At present, the components of gunpowder (sulfur, nitrate, carbon) are concentrated in Li-S batteries, which may be potentially dangerous during commercial use. According to the new discovery of the role of LiNO3 additives in Li-S batteries in this work, future research work can be based on the migration number theory to find other electrolyte additives that can promote the migration number of lithium ions and interact with polysulfide anions. LiNO3 additives, thereby reducing the potential dangers of Li-S batteries in use.

Single-ion-conducting polymer electrolytes are attractive to use in lithium batteries as the transference number of the lithium cation approaches unity. This helps prevent concentration gradients a...

The dehydrogenation of 2,3-butanediol (BDO) to 3-hydroxybutanone (HBO) was studies over Li cation-doped CuZnAl catalysts. The catalyst samples were characterized by XRD, XPS, H -TPR and SEM techniques. The characterization results showing that doping with Li cation obviously modified the surface morphology of CuZnAl catalysts; decreased the reduction temperature of CuZnAl catalysts; and finally increased the amount of Cu active sites. The reaction results showing that, Li modified CuZnAl catalysts obviously enhanced the selectivity of the dehydrogenation of BDO to HBO by inhibiting the dehydration of BDO. The Li(2%)–Cu(44%)–Zn(38%)–Al(16%) exhibited the highest activity for dehydrogenation of BDO, with the conversion rate of BDO is 72.4% and the selectivity of HBO is 95.9% at 260°C. This catalyst shows excellent stability for more than 100h without significant deactivation. 2

The synthesis and spectral and structural descriptions of two salts of formulas {[Li][Li(H2O)(μ-CN)3]}[W(CN)3(bpy)] (1) and {Li}{[Li(μ-CN)2][Li(μ-CN)3]μ-Cl}[W(CN)(bpy)]·2H2O (2) were described. The structural investigation shows the influence of the size and charge of Li+ on the nature of the CN−/Li+ interaction and thus on the structure of the compounds. Both salts crystallize in the triclinic P space group with very similar cell parameters (a, b and c differ by no more than 0.05 A, α, β and γ less than 1°, and cell volume less than 4 A3) in spite of the different complex formulas. In 1, two different lithium cations are observed. Only one compensates the anion charge, while the second one is tetrahedral and forms a complicated 1D network via three nitrogen atoms of cyano ligands trans to a bpy molecule. The molecular wires connect neighbouring molecules only by weak intermolecular interactions. In 2, the 2D structure, with layers connected only by π–π stacking interactions, is observed. Lithium cations are involved in bonds with the nitrogen of cyano ligands.

Deprotonation of the fluorenyl-tethered imidazolinium salt [9-(C13H9)C2H4N(CH)C2H4N(2,4,6-Me3C6H2)][BF4] gave a spirocyclic compound that reacted with a synergic mixture of LiPh/LiN(SiMe3)2 or LinBu/LiN(SiMe3)2 to give a dilithium complex incorporating a bridging N(SiMe3)2 ligand. In contrast, deprotonation of the imidazolium salt [9-(C13H9)C2H4N(CH)C2H2N(Me)][Br] instead yielded the free NHC, which reacted with nBuLi to form a dimeric, NHC-bridged dilithium complex. Addition of LiN(SiMe3)2 led to coordination and the formation of a dilithium complex with a bridging N(SiMe3)2 ligand, which was characterised in the solid state as a 1D coordination polymer. The reaction of 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene (SIPr) with lithium indenide and lithium fluorenide gave soluble species with terminal binding of the NHC to the lithium cation and η5 coordination of indenyl or fluorenyl. A symmetrical bridging mode for an NHC donor was therefore observed only if a tethered fluorenyl anion was present with no additional amide ligand.

International audience; We report herein the synthesis of a new NHC-stabilised borane complexe featuring a weakly coordinating anion, namely a pentaorganosilicate, on the NHC backbone. The synthesis can be achieved from a zwitterionic abnormal silicate-imidazolium adduct by deprotonation with a strong base followed by quenching with a borane transfer agent. Alternatively, the IPr-BH 3 complex can also be deprotonated and the resulting vinylanion is trapped by a tetravalent spirosilane. The first structural data on a lithium derivative of an anionic NHC-borane complex functionalized by a silicate have been obtained and reveal an interaction between the three hydrogens of the borane and the lithium cation. Assessment of the reactivity highlights the higher hydridicity of the anionic NHCborane compared to the parent IPr-BH 3. Finally, electronic properties of this new species have been evaluated by means of DFT calculations and the presence of the silicate on the NHC backbone raises the HOMO which can in part explain the high hydride-donor abilities. This is consistent with the smooth reduction of an aldehyde without Lewis acid additive.

MP2/aug-cc-pVTZ calculations were carried out on complexes wherein the proton or the lithium cation is located between π-electron systems, or between π-electron and σ-electron units. The acetylene or its fluorine and lithium derivatives act as the Lewis base π-electron species similarly to molecular hydrogen, which acts as the electron donor via its σ-electrons. These complexes may be classified as linked by π-H∙∙∙π/σ hydrogen bonds and π-Li∙∙∙π/σ lithium bonds. The properties of these interactions are discussed, and particularly the Lewis acid units are analyzed, because multi-center π-H or π-Li covalent bonds may occur in these systems. Various theoretical approaches were applied here to analyze the above-mentioned interactions—the Quantum Theory of Atoms in Molecules (QTAIM), the Symmetry-Adapted Perturbation Theory (SAPT) and the Non-Covalent Interaction (NCI) method.

Mass spectrometric analysis of lignin for developing biomaterials requires advances of characterization techniques. Positive ion mass spectrometry of lignin model compounds using lithium has recently been explored as a viable alternative to current negative mode techniques. To date, little is known about the impact of lithium adduct ion formation on relative response factors of lignin and lignin decomposition products. In this contribution, we report estimates of lithium cation basicity for synthetic monolignols H, G and S using Cooks’ kinetic method on a linear quadrupole ion trap mass spectrometer. Optimized geometries and interaction energies have also been calculated by DFT methods to quantify the electrostatic cation coordination. Based on a combination of experimental and computational evidence, lithium appears to preferentially bind to the phenol and methoxy substituents on the aromatic ring of monolignols. The strength of this interaction increases with the number of methoxy substituents (S > G > H). This work serves as a basis of understanding for future work in developing lithium adducted lignin mass spectrometric analytical methods.

We demonstrate that lithium metal is sparingly soluble in poly(ethylene oxide) (PEO). 7Li NMR shows that when a PEO sample is placed in contact with lithium metal at elevated temperatures, a lithium species dissolves and diffuses into the bulk polymer. A lithium/PEO/lithium electrochemical cell, containing no lithium salts, shows increasing conductivity over time when annealed at 120 °C. Chronoamperometry shows that the annealed cell obeys Ohm’s law, implying that conduction occurs without the development of concentration gradients. To explain the results, it is proposed that atomic lithium dissolves into PEO, where it exists as a lithium cation and free electron. The dissolution of lithium also affects the phase behavior of block copolymer electrolytes. These observations explain the strong adhesion between lithium metal and PEO and have important implications for lithium metal battery systems that contain PEO-based electrolytes.

The question of the number of carbonate molecules in the first coordination shell of the lithium cation is outstanding. This query has been already answered for cyclic carbonates like ethylene carbonate (EC), demonstrating a coordination number of 4. In this work, we attempt to solve such a problem for three linear carbonates including dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). For this purpose, we have calculated various Li+–carbonate clusters with the coordination number from 1 to 4 by using density functional theory at the B3LYP/6-31+G (d, p) level. A discussion has been made on favoring of Li+···O=C interaction over Li+···OC2 interaction in the coordination process of carbonates to the lithium cation. The IR spectra of the optimized clusters have been also computed to improve understanding of the Li+ interaction with the carbonyl group of the solvent. Thermodynamic functions of the coordination process such as Gibbs free energy (ΔG), heat of formation (ΔH), and entropy (ΔS) as well as binding energy (Ebin) have been obtained to explain the effect of alkyl chain of carbonates on the coordination. Our calculations show that the number of linear carbonate solvents coordinated directly to the lithium cation can be up to 3. Furthermore, it is observed that the interaction strength of the studied three solvents with Li+ is in the sequence DEC > EMC > DMC. This indicates that the dissociation constant of a lithium salt as an effective parameter for lithium-ion batteries could be higher in diethyl carbonate.

For the first time, the effect of minor structural changes to the electrolyte salt on solution properties is investigated experimentally. It was achieved by decomposition of the overall changes into individual components. It allowed to obtain information on the contradicting effects influence on the final result. This study is focused on comparison of two lithium salts: lithium 4,5-dicyano-2-(trifluoromethyl) imidazolide (LiTDI) and lithium 4,5-dicyano-2-(pentafluoroethyl) imidazolide (LiPDI). LiTDI is a very promising salt for lithium-ion battery application. PDI− anion differs from TDI− only in length of perfluorinated alkyl chain. Triethylene glycol dimethyl ether (triglyme) solutions of both salts in a wide range of concentrations were prepared. Triglyme was chosen as a solvent due to number of oxygen atoms which allows for fulfilment of lithium cation coordination sphere. Use of such similar salts in a model system allows us to find the correlation between salt structure and properties of electrolyte. Conductivity, viscosity, lithium transference number, thermal properties and FTIR spectra were measured for all solutions. Ionic fractions were also estimated by Fuoss-Kraus formalism. Obtained results showed that electrochemical properties of electrolyte are result of several opposing factors. Transference numbers are mostly dependent on association. We have also observed interesting correlation between thermal properties and conductivity.

Compounds containing biguanide moiety, such as buformin, phenformin, and metformin are well recognized for their antihyperglycaemic action. Imeglimin is a dihydro-1,3,5-triazine that can be conside...

A series of halogen bonding and chalcogen bonding phenanthroline containing heteroditopic macrocyclic receptors exhibit cooperative recognition of lithium halide (LiX) ion-pairs. Quantitative 1H NMR ion-pair titration experiments in CDCl3 : CD3CN (1 : 1, v/v) reveal a co-bound lithium cation switches on halide anion binding, most notably with the halogen bonding host system. The employment of bis- iodo- and telluromethyl-triazole sigma–hole donor motifs endows contrasting halide anion selectivity and binding affinity, with the halogen bonding ditopic host capable of exclusively binding lithium chloride whereas the chalcogen bonding ditopic receptor displays notable selectivity for lithium iodide over lithium bromide. Preliminary solid–liquid extraction experiments demonstrate the potential of sigma–hole mediated ion-pair recognition as a promising strategy for lithium salt recovery.

As the world transitions away from fossil energy to green and renewable energy,electrochemical energy storage increasingly becomes a vital component of the mix to conduct thistransition. The central goal in developing next-generation batteries is to maximize gravimetric andvolumetric energy density, battery cycle life and improve safety. All solid-state batteries using asolid electrolyte and a lithium metal anode represent one of the most promising technologies thatcan achieve this goal. Highly conductive solid electrolytes (>10 mS·cm-1) are the key componentto remove the safety concerns inherent with flammable organic liquid electrolyte and achieve highenergy density by enabling high active material loading. Considering a range of inorganic solidelectrolytes that haven been developed to date, sulfide solid electrolytes exhibit highest ionicconductivity that even surpasses that of conventional organic liquid electrolytes. Argyrodite-structured sulfide solid electrolytes are one of the most promising materials in this class and arecurrently the dominantly used solid electrolyte for all solid-state battery fabrication. Argyroditesolid electrolytes are particularly appealing, owing to their ultra-high Li-ion conductivity, quasistablesolid electrolyte interphase (SEI) formed with Li metal and their ability to be prepared viascalable solution-assisted synthesis approaches. These factors are all vital for commercialapplications.In this Account, we afford an overview of our recent development of several argyroditesuperionic conductors, including Li6.6Si0.6Sb0.5S5I (24 mS·cm-1), Li6.6Ge0.6P0.4S5I (18 mS·cm-1) andLi5.5PS4.5Cl1.5 (12 mS·cm-1), and a comprehensive understanding of the origin of the underlyinghigh conductivity: namely sulfide/halide anion site-disorder and Li cation site disorder. A highdegree of sulfide/halide anion site-disorder (changes in anion distribution) modifies the anioniccharge that in turn strongly influences the lithium distribution. A more inhomogeneous chargedistribution in anion-disordered systems generates a spatially diffuse and delocalized lithiumdensity resulting in faster ionic transport. Lithium cation site-disorder generated by increasing Licarrier concentration through aliovalent substitution, creates high-energy interstitial sites for Liion diffusion which activate concerted ion migration and flatten the energy landscape for Li iondiffusion. This enables high conductivity in Li-rich argyrodite superionic conductors. Theseconcepts are also expected to promote rational new solid electrolyte design and fundamentalunderstanding of the structure - ion transport relationships in inorganic ionic conductors.Collectively, a comprehensive and deep understanding of the interphase formation betweenargyrodite solid electrolytes and cathode active materials/Li metal, and the failure mechanism ofall solid-state batteries with argyrodite solid electrolytes, will lead to the bottom-up engineering of the cathode/anode-solid electrolyte interfaces, which will accelerate the development of safe, highenergy density all solid-state lithium batteries.

Lithium metal is among the most promising anodes for the next generation of batteries due to its high theoretical energy density and high capacity. Challenges such as extreme reactivity and lithium dendrite formation have kept lithium metal anodes away from practical applications. However, the underlying mechanisms of Li ion deposition from the electrolyte solution onto the anode surface are still poorly understood due to their inherent complexity. In this work, density functional theory calculations and thermodynamic integration via constrained molecular dynamics simulations are conducted to study the electron and ion transfer between lithium metal slab and the electrolyte in absence of an external field. We explore the effect of the solvent chemistry and structure, distance of the solvated complex from the surface, anion-cation separation, and concentration of Li-salts on the deposition of lithium ions from the electrolyte phase onto the surface. Ethylene carbonate (EC), 1,2-dimethoxyethane (DME), 1,3-dioxolane (DOL), and mixtures of them are used as solvents. These species compete with the salt anion and the Li cation for electron transfer from the surface. It is found that the structure and properties of the solvation shell around the lithium cation has a great influence on the ability of the cation to diffuse as well as on its surrounding electron environment. DME molecules allow easier motion of the lithium ion compared with EC and DOL molecules. The slow growth approach allows the study of energy barriers for the ion diffusion and desolvation during the deposition pathway. This method helps elucidating the underlying mechanisms on lithium-ion deposition and provides a better understanding of the early stages of Li nucleation.

Lithium cations have been shown to impart an electrostatic Stark effect on molecules bound to mesoporous metal oxides commonly used in dye-sensitized solar cells. Herein, using the Barrera-Crivelli-Loeb theoretical model accompanied by Time Dependent Density Functional Theory calculations, we examined the influence that lithium cations have on the performance of dye-sensitized solar cells that incorporate [Ru(dmb)2(dcbH)]2+ sensitizers, where dmb is 4,4′-dimethyl-2,2′-bipyridine and dcbH is 4,4′-dicarboxylic acid-2,2′-bipyridine was examined. Simulations suggest that an enhanced photocurrent occurs in the presence of lithium cations, which is attributed to the photochemical generation of an excited-state dye–lithium adduct. In this adduct, a lithium cation is interacting with the carbonyl moieties of the dcbH ligands, which results in a bathochromic shift of the [Ru(dmb)2(dcbH)]2+ metal-to-ligand charge-transfer spectral band. This shift in absorption can be canceled by introducing a hypothetical dipolar electric field of 7.3 MV/cm, in good agreement with experimentally reported values for Stark effects observed under solar excitation of TiO2 functionalized with these types of sensitizer molecules. This indicates that lithium cations not only interact with the metal-oxide semiconductor, as shown previously, but also interact directly with the dye upon photoexcitation, something that should be considered when designing and evaluating new sensitizers.

Ionic liquids have gained immense popularity in recent decades due to a combination of unique properties. Despite the widespread use of ionic liquids mixtures with aprotic dipolar solvents in electrochemistry, it remains relevant to predict their macroscopic, primarily transport, properties based on the microscopic picture of the entire set of interparticle interactions in such systems. The method of molecular dynamics simulation (MDS) is one of the most powerful tools for solving problems of this kind. However, one of the unsolved problems of the classical MDS of ion-molecular systems is the correct accounting of polarization effects. Recently it was proposed to use a variation of the effective ion charges in solutions to solve this task. This paper presents the results of the MDS structural and dynamic properties of 1-butyl-3-methylimidazolium (BmimBF4) and lithium (LiBF4) tetrafluoroborates solutions in propylene carbonate (PC) at 298.15 K in NPT ensemble using GROMACS and MDNAES software packages. The possibility of reproducing the experimental dynamic properties (diffusion coefficients of cations and solvent, viscosity, and electrical conductivity) of binary systems based on mixtures of ionic liquids with PC in a wide concentration range was shown. Polarization effects were taken into account by reducing the partial charges of the ion atoms. The structure of the solvation shell of cations was studied within the framework of radial distribution functions, distribution of coordination numbers and the presence of hydrogen bonds between the organic cation and solvent molecules. The results point to stronger and more structured solvation shell of the Li+ cation compared to Bmim+, which is consistent with the conclusions about the mobility of these cations. The reorientation times of propylene carbonate molecules and their lifetimes in the framework of the first solvation shells of the cations are several times higher for the lithium cation.

Differential ion mobility spectrometry (DIMS) can be used to separate isomeric and isobaric ions, which are difficult to distinguish with mass spectrometry alone. Three peaks were observed while performing DIMS-MS for both lithium cationized glucose and lithium cationized levoglucosan. Glucose has a large number of potential structures for its small size. The different peaks could be caused by differences in glucose anomericity, pyranose versus furanose forms, ring conformation, or the lithium cation binding site. However, the bicyclic structure of levoglucosan is more constrained and less likely to result in different structures than glucose. The three peaks for both compounds were found to originate from the monomer, post-DIMS fragmentation of a homodimer, and post-DIMS fragmentation of a heterodimer with a common contaminant, erucamide. This post-DIMS fragmentation occurs in the ion transfer optics and can lead to erroneous conclusions about the peaks in a DIMS spectrum where dimers are present. Dimers are commonly observed when using metal cationization, where over 10% of the glucose and levoglucosan was observed as a lithium cation bound dimer, even at concentrations as low as 0.1 μM.

For lithium halides, LiX (X = Cl, Br and I), hydrates with a water content of 1, 2, 3 and 5 moles of water per formula unit are known as phases in aqueous solid–liquid equilibria. The crystal structures of the monohydrates of LiCl and LiBr are known, but no crystal structures have been reported so far for the higher hydrates, apart from LiI·3H2O. In this study, the crystal structures of the di- and trihydrates of lithium chloride, lithium bromide and lithium iodide, and the pentahydrates of lithium chloride and lithium bromide have been determined. In each hydrate, the lithium cation is coordinated octahedrally. The dihydrates crystallize in the NaCl·2H2O or NaI·2H2O type structure. Surprisingly, in the tri- and pentahydrates of LiCl and LiBr, one water molecule per Li+ ion remains uncoordinated. For LiI·3H2O, the LiClO4·3H2O structure type was confirmed and the H-atom positions have been fixed. The hydrogen-bond networks in the various structures are discussed in detail. Contrary to the monohydrates, the structures of the higher hydrates show no disorder.

Li6-xZr2-xAxO7 (A = Nb, Ta) system with 0 &lt, x &lt, 0.30 is synthesized by glycine-nitrate method. Boundaries of solid solutions based on monoclinic Li6Zr2O7 are determined, temperature (200–600 °C) and concentration dependences of conductivity are investigated. It is shown that monoclinic Li6Zr2O7 exhibits better transport properties compared to its triclinic modification. Li5.8Zr1.8Nb(Ta)0.2O7 solid solutions have a higher lithium-cation conductivity at 300 °C compared to solid electrolytes based on other lithium zirconates due the “open” structure of monoclinic Li6Zr2O7 and a high solubility of the doping cations.

The new polymorph of lithium tetra­chlorido­aluminate, LiAlCl4, adopts a defect wurtz-stannite-type of structure and is metastable., Dissolving lithium chloride and aluminium chloride in boiling para- or meta-xylene and keeping the colourless solution at room temperature led to crystal growth of a new modification of lithium tetra­chlorido­aluminate, LiAlCl4, which represents a second modification (oP12, Pmn21) of the ternary salt besides the long known monoclinic form [LiAlCl4(mP24, P21/c); Mairesse et al. (1977 ▸). Cryst. Struct. Commun. 6, 15–18]. The crystal structures of both modifications can be described as slightly distorted hexa­gonal closest packings of chloride anions. While the lithium cations in LiAlCl4(mP24) are in octa­hedral coordination and the aluminium and lithium ions in the solid of ortho­rhom­bic LiAlCl4 occupy tetra­hedral inter­stices with site symmetries m and 1, respectively, the lithium cation site being half-occupied (defect wurtz-stannite-type structure). From differential scanning calorimetry (DSC) measurements, no evidence for a phase transition of the ortho­rhom­bic modification is found until the material melts at 148 °C (T peak = 152 °C). The melting point is nearly identical to the literature data for LiAlCl4(mP24) [146 °C; Weppner & Huggins (1976 ▸). J. Electrochem. Soc. 124, 35–38]. From the melts of both polymorphs, the monoclinic modification recrystallizes.

To shed light on the performances of the ionic-liquids (ILs) as electrolyte in lithium metal batteries, we have studied 1-R-1-methyl pyrrolidinium [RmPyrr]+, 1-R-1-methylpiperidinium [RmPiP]+, and 1-R-1-methylazepanium [RmAzp]+ as cations with R = MeOCH2CH2- and [NTF2]- as anion, ion pairs as pure IL's and ion pair plus Li as doped IL's by ab-initio methods. Obtained structural parameters and electronic properties from natural bond orbital, atom in molecule and density of states analyses reveal that in the presence of Li all active electrophile and nucleophile sites of the ion pair vanish. The ion pair binding energy reduces in the doped ion pairs which suggests the elevation of the ILs ionic conductivity in a quantum structure property relationship regime.

NiO based p-type aqueous dye-sensitized solar cells (p-DSCs) with various lithium ion concentrations in electrolytes have been studied using a series of techniques. The existence of lithium ion can form an inside electric field near the NiO working electrode surface and restrain the charge recombination, as is demonstrated by the electrochemical impedance spectroscopy measurement. The narrowing of driving force after the addition of lithium ion does not affect the efficient charge injection, while the widened energetic difference between the valance band of NiO and the redox potential of the electrolyte contributes to the improvement of photovoltage. As a result, the optimal concentration of lithium ion is found to be 1.35 M and the corresponding average power conversion efficiency of P1-dye-sensitized aqueous p-DSCs is 0.40% (measured under standard AM 1.5 G test conditions), which almost doubles that without lithium ion addition. The results suggest a very facile method for the improvement of the photovoltaic performance of p-type aqueous DSCs.

The model potential approach is well adapted to study atomic and molecular systems involving a single active electron. Such is the case of the alkali-dimer lithium cation Li + 2. However, a comparison of the model potential results of Magnier et al.[1] and those based on ab-initio techniques [2, 3, 4] raises a number of questions related to the existence of an important disagreement regarding several excited states,which are found to be repulsive by Magnier et al. [1] but attractive when ab-initio techniques are employed. In this paper, we propose to re-investigate the Li + 2 system, using a model potential technique to compute the adiabatic energy curves and the molecular spec-troscopic constants. Our aim is to clarify whether this disagreement between the ab-initio and model potential methods originates from some conceptual defect of the model potential technique or whether there is some source of error in the calculations of Magnier et al. [1].

The effect of number of CH3 groups (n) on the cation (H+, Li+, Na+, Al+, CH3+) affinity, polarizability, and dipole moment of 14 simple molecules was investigated. Linear correlations were observed between the polarizabilities and the number of methyl groups. The variations of the cation affinities and dipole moments with the number of methyl groups (n) were not linear, and a quadratic function was proposed for obtaining a good fit of the experimental data. Also, because the proton affinities (PA), lithium cation affinities (LCA), sodium cation affinities (SCA), aluminum cation affinity (AlCA), and methyl cation affinity (MCA) varied quadratically with polarizabilities (α), a formula of the form [cation affinities] = a + bα + cα2 was proposed. After correction of the PAs, LCAs, SCAs, AlCA, and MCA for the dipole/charge interaction (Eμ), linear relationships were observed between the corrected cation affinities and n or α. The contribution of Eμ to PA and MCA was small (less than 20%), and its contribution...

he mechanistic details of the aldol addition of N-amino cyclic carbamate (ACC) hydrazones is provided herein from both an experimental and computational perspective. When the transformation is carried out at room temperature the anti-aldol product is formed exclusively. Under these conditions the anti- and syn-aldolate intermediates are in equilibrium and the transformation is under thermodynamic control. The anti-aldolate that leads to the anti-aldol product was calculated to be 3.7 kcal mol-1 lower in energy at room temperature than that leading to the syn-aldol product, which sufficiently accounts for the exclusive formation of the anti-aldol product. When the reaction is conducted at -78 °C it is under kinetic control and favors formation of the syn-aldol addition product. In this case, it was found that a solvent separated aza-enolate anion and aldehyde form a σ-intermediate in which the lithium cation is coordinated to the aldehyde. The σ-intermediate collapses with a very small activation barrier to form the β-alkoxy hydrazone intermediate. The chiral nonracemic lithium aza-enolate discriminates between the two diastereotopic faces of the pro-chiral aldehyde, and there is no rapid direct pathway that interconverts the two diastereomeric intermediates. Consequently, the reaction does not follow the Curtin-Hammett principle and the stereochemical outcome at low temperature instead depends on the relative energies of the two σ-intermediates.

The supporting information is attached. Aliphatic polycarbonates have emerged as promising polymer electrolytes due to their combination of moderate ionic conductivity and high lithium transference numbers. However, the mechanical properties of the aliphatic polycarbonates polymer electrolytes are usually weak due to the low molecular weight achieved and plasticization effect of the added lithium salt. In this article, we present a copolymer having poly(ethylene oxide) segments linked by carbonate groups with cross-linkable methacrylic pendant groups. Once the polymer and the lithium salt were mixed, the poly(ethylene oxide carbonate) was cross-linked by UV light producing a free standing solid polymer electrolyte (SPE). Different SPE formulations were designed by varying the LiTFSI concentration within the polymer matrix showing the highest ionic conductivity of 1.3·10−3 S cm−1 and a lithium transference number of 0.59 at 70 °C. 7Li solid-state NMR experiments were used to correlate the lithium cation environment and dynamics with ionic conductivity. At the same temperature the electrochemical stability window was analyzed, and a reasonable value of 4.9 V was achieved. The study was complemented by mechanical and thermal stability measurements. Finally, the optimized UV-cross-linked poly(ethylene oxide carbonate) was tested as electrolyte in lithium metal symmetric cell at 70 °C, showing low over-potential values and a stable solid electrolyte interphase layer. We are grateful to the financial support of the European Research Council by Starting Grant Innovative Polymers for Energy Storage (iPes) 306250 and the Basque Government through ETORTEK Energigune 2013 and IT 999-16. Leire Meabe thanks Spanish Ministry of Education, Culture and Sport for the predoctoral FPU fellowship received to carry out this work. The authors would like to thank the European Commission for their financial support through the project SUSPOL-EJD 642671 and the Gobierno Vasco/Eusko Jaurlaritza (IT 999-16). The authors thank for technical and human support provided by SGIker of UPV/EHU for the NMR facilities of Gipuzkoa campus.

This work reveals first principle results of the endohedral fullerenes made from neutral or charged single atomic lithium (Li or Li+) encapsulated in fullerenes with various cage sizes. According to the calculated binding energies, it is found that the encapsulation of a single lithium atom is energetically more favorable than that of lithium cation. Lithium, in both atomic and cationic forms, exhibits a clear tendency to depart from the center in large cages. Interaction effects dominate the whole encapsulation process of lithium to carbon cages. Further, the nature of the interaction between Li (or Li+) and carbon cages is discussed based on reduced density gradient, energy decomposition analysis, and charge transfer.

Glycine-nitrate method is used to synthesize samples in Li6-2xMxZr2O7 (M = Mg, Ca, Zn) systems. Boundaries of single-phase regions of solid solutions based on monoclinic Li6Zr2O7 are roughly determined, temperature dependencies across the range of 300–600°С and concentration dependencies of their conductivity are studied. The maximum lithium cation conductivity of the synthesized solid solutions exceeds the conductivity of undoped Li6Zr2O7 by more than two orders of magnitude. The obtained results are compared with the available literature data on the transport properties of Li6Zr2O7 and solid solutions based on it. The influence of electronegativity of M dopants on the transport properties of the investigated solid electrolytes is studied.

The impact of the association of lithium cation with NCS– ion in acetonitrile on the vibrational spectrum was studied by the density-functional method in the B3LYP/6-31+G(d,p) approximation. The best agreement between experimental and calculated ionic association data was achieved taking into account the nonspecific solvation, oversolvation, and solubility of ionic complexes within the discrete-continuum model. The microstructures of the thiocyanate ion in a contact ion pair with lithium cation and ion-pair dimer and trimer in acetonitrile were established.

Over the years numerous mixes of chemical compounds have been tried in the electrolytes of dye-sensitized solar cells in efforts to improve their efficiency. How these chemicals interact with each other and the photoelectrode has received surprisingly little attention. Here we report results from a systematic study of two I–/I3– electrolytes and their additives using infrared and Raman spectroscopy together with quantum chemical calculations. In the LiI electrolyte competing interactions between lithium cation and the solvent MPN and the additives TBP, NMBI, and GuSCN were identified. These interactions could inhibit the interaction of lithium ions with the TiO2 surface. It was found that under Raman excitation of PMII solution in contact with the photoelectrode, efficient generation of I3– takes place. For LiI solution, in addition, a Dye–I2 complex is formed. The results could be explained by diffusion-limited buildup of I3– and depletion of I– concentrations in the focal area of the excitation beam and by reduction of I3– via conduction band electrons of TiO2 beyond the focal region. To explain the formation of Dye–I2 complexes in the LiI electrolyte solutions a multistep regeneration mechanism is proposed. It was found that GuSCN reduces the I3– concentration in the electrolyte solutions studied; in the LiI electrolyte in addition it binds to lithium ions and nearly depletes the Dye–I2 complexes. From infrared spectra it became clear that preventing water from entering the DSCs during the preparation stages in ambient air is a demanding task. The identified interactions paint an intriguing new photochemical landscape of the function of the dye-sensitized solar cells giving guidelines for further development of the devices.

The hydrogenolysis of glycerol was performed over a Pt/C catalyst in combination with several alkali metal hydroxides and their salts. LiOH was found to be an effective promoter for the selective hydrogenolysis of glycerol to 1,2-propanediol. Hydroxyl ions are the main factor to promote the reaction process by dehydration of the glyceraldehyde intermediate. Lithium ions play a role in assisting the dehydrogenation of glycerol to glyceraldehyde, because they have the right size to coordinate with the alkoxide species. A possible surface reaction mechanism involving the participation of lithium ions was proposed to account for the results obtained in the study.

The normalised polarity E and Kamlet-Taft parameters of recently described solvate ionic liquids, composed of lithium bis(trifluoromethyl)sulfonimide (LiTFSI) in tri- () or tetraglyme () have been determined and compared to the parent glyme ( and ). We show that these solvate ionic liquids have a high polarity (, (E) = 1.03; , (E) = 1.03) and display very high electron pair accepting characteristics (, α = 1.32; , α = 1.35). Molecular dynamics simulations suggest that the chelated lithium cation is responsible for this observation. The relatively small hydrogen bond acceptor (β) values for these systems (, β = 0.41; , β = 0.37) are thought to be due primarily to the TFSI anion, which is supplemented slightly by the glyme oxygen atom. In addition, these solvate ionic liquids are found to have a high polarisability (, π* = 0.94; , π* = 0.90).

International audience; Reversible dimerization of the anion radicals of carbonyl compounds was studied by cyclic voltammetry, chronoamperometry, electrolysis, digital simulation and quantum chemical calculations using electroreduction of 9-fluorenone in DMF/0.1 M Bu4NClO4 as an example. The experimental data confirmed that this reaction is thermodynamically unfavorable as it was predicted by DFT calculations. In contrast with some other anion radicals, neither ion pairing of 9-fluorenone anion radicals with lithium cation nor their hydrogen bonding with water shifts the dimerization equilibrium to the dimeric product. Reversibility of the dimerization decreases in the presence of phenol due to the protonation of the dimeric dianion and to the irreversibility of dimerization of the anion radical – phenol complexes. The contribution of these two pathways to general hydrodimerization process is discussed. © 2020 Elsevier Ltd

The effect of the addition of lithium trifluoromethanesulfonate (LiCF_3SO_3) on the linear viscoelastic properties, crystallization behavior, and mechanical properties of poly(lactic acid) (PLA) was studied. The glass transition temperature (T_g) was enhanced by adding LiCF_3SO_3, without any loss of transparency of the PLA. This was attributed to the ion-dipole interaction between the lithium cation and oxygen atom in the PLA carbonyl group. The interaction weakened at higher temperature. Consequently, the rheological terminal region was clearly detected, which suggested that the system possessed good melt-processability. The Young’s modulus and yield stress at room temperature were also enhanced by the addition of LiCF_3SO_3, although the toughness was reduced due to the brittle failure. Finally, the presence of LiCF_3SO_3 retarded the crystallization of PLA, because the segmental motion of the PLA chains was reduced.

Lithium stripping is a crucial process coupled with lithium deposition during the cycling of Li metal batteries. Lithium deposition has been widely studied, whereas stripping as a subsurface process has rarely been investigated. Here we reveal the fundamental mechanism of stripping on lithium by visualizing the interface between stripped lithium and the solid electrolyte interphase (SEI). We observed nanovoids formed between lithium and the SEI layer after stripping, which are attributed to the accumulation of lithium metal vacancies. High-rate dissolution of lithium causes vigorous growth and subsequent aggregation of voids, followed by the collapse of the SEI layer, i.e., pitting. We systematically measured the lithium polarization behavior during stripping and find that the lithium cation diffusion through the SEI layer is the rate-determining step. Nonuniform sites on typical lithium surfaces, such as grain boundaries and slip lines, greatly accelerated the local dissolution of lithium. The deeper understanding of this buried interface stripping process provides beneficial clues for future lithium anode and electrolyte design.

The structure of crystalline [60]fullerene with a lithium cation inside (Li + @C 60 ) was determined by synchrotron radiation X-ray diffraction measurements to understand the electrostatic and thermal properties of the encapsulated Li + cation. Although the C 60 cages show severe orientation disorder in [Li + @C 60 ](TFPB − )·C 4 H 10 O and [Li + @C 60 ](TFSI − )·CH 2 Cl 2 , the Li + cations are rather ordered at specific positions by electrostatic interactions with coordinated anions outside the C 60 cage. The Li + @C 60 molecules in [Li + @C 60 ](ClO 4 − ) with a rock-salt-type cubic structure are fully disordered with almost uniform spherical shell charge densities even at 100 K by octahedral coordination of ClO 4 − tetrahedra and show no orientation ordering, unlike [Li + @C 60 ](PF 6 − ) and pristine C 60 . Single-bonded (Li + @C 60 − ) 2 dimers in [Li + @C 60 − ](NiOEP)⋅CH 2 Cl 2 are thermally stable even at 400 K and form Li + –C bonds which are shorter than Li + –C bonds in [Li + @C 60 ](PF 6 − ) and suppress the rotational motion of the Li + cations.

Lithium bis(trifluoromethane) sulfonamide (TFSI) is a promising electrolyte salt in lithium batteries, due to its good conductivity and high dissociation between the lithium cation and its anion. By tethering N-pentane trifluoromethane sulfonamide (C5NHTf), a TFSI analogue molecule, onto the surface of silica nanoparticle as a monolayer coverage should increase the Li(+) transference number to unity since anions bound to particles have reduced mobilities. Silica polymer composite has better mechanical property than that of the pure PEO. Analogously trifluoromethane sulfonic aminoethyl methacrylate (TfMA), a TFSI analogue vinyl monomer, was polymerized on silica nanoparticle surface as a multilayer coverage. Anchored polyelectrolytes to particle surfaces offer multiple sites for anions, and in principle the carrier concentration would increase arbitrarily and approach the carrier concentration of the bulk polyelectrolyte. Monolayer grafted nanoparticles have a lithium content of 1.2 × 10(-3) g Li/g, and multilayer grafted nanoparticles have a lithium content over an order higher at 2 × 10(-2) g Li/g. Electrolytes made from monolayer grafted particles exhibit a weak conductivity dependence on temperature, exhibiting an ionic conductivity in the range of 10(-6) S/cm when temperatures increase to 80 °C. While electrolytes made from multilayer grafted particles show a steep increase in conductivity with temperature with an ionic conductivity increase to 3 × 10(-5) S/cm at 80 °C, with an O/Li ratio of 32.

Raman study of cation and anion solvation in dimethyl sulfoxide, propylene carbonate and dimethyl carbonate solutions of six lithium salts has been performed in the concentration range from 0.05 to 0.25 molar fraction of a salt. The dependences of the amount of the solvent particles involved in dimerization, hydrogen bonding, and solvation have been determined, and the mean solvation numbers have been found. It is concluded that in all solutions studied, notwithstanding the differences in the physical properties of the solvent and in the structure of the anion, both the lithium cation and the anion solvation equilibria are quantitatively similar. In all cases, solvation numbers of cations are close to two and do not vary with the growth of concentration. In particular, in molten LiX·4S solvates, LiS 4 + entities expected from the phase diagrams do not exist. It has been found that for the solvent molecules in dimers and in solvation spheres, non-coincidences between vibrational frequencies of isotropic and anisotropic lines, Δ ν NCE = ν aniso − ν iso are of opposite signs signifying that the mutual orientation of molecules is different. In all systems studied, solvation numbers of anions decrease if the salt content is growing and are close to four in concentrated solutions. These striking similarities in the structure and concentration of solvated entities clearly signify that solvation phenomena have no decisive importance in determining the properties of salt systems.