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The previously introduced workflow to achieve an energetically and structurally optimized description of frontier bonds in quantum mechanical/molecular mechanics (QM/MM)‐type applications was extended into the regime of computational material sciences at the example of a layered carbon model systems. Optimized QM/MM link bond parameters at HSEsol/6‐311G(d,p) and self‐consistent density functional tight binding (SCC‐DFTB) were derived for graphitic systems, enabling detailed investigation of specific structure motifs occurring in graphene‐derived structures via quantum‐chemical calculations. Exemplary molecular dynamics (MD) simulations in the isochoric‐isothermic (NVT) ensemble were carried out to study the intercalation of lithium and the properties of the Stone–Thrower–Wales defect. The diffusivity of lithium as well as hydrogen and proton adsorption on a defective graphene surface served as additional example. The results of the QM/MM MD simulations provide detailed insight into the applicability of the employed link‐bond strategy when studying intercalation and adsorption properties of graphitic materials. [ABSTRACT FROM AUTHOR]

The bottleneck in the implementation of hybrid lithium-sodium-ion batteries is the lack of anode materials with a desired rate capability. Herein, we provide an in-depth examination of the Li-storage performance of sodium titanate nanowires as negative electrodes in hybrid Li,Na-ion batteries. Titanate nanowires were prepared by a simple and reproducible hydrothermal method. At a low reaction pressure, the well-isolated nanowires are formed, while by increasing the reaction pressure from 2 to 30 bar, the isolated nanowires tend to bundle. In nanowires, the local coordinations of Na and Ti atoms deviate from those in Na2Ti3O7 and Na2Ti6O13 and slightly depend on the reaction pressure. During the annealing at 350 °C, both Na and Ti coordinations undergo further changes. The nanowires are highly defective, and they easily crystallize into Na2Ti6O13 and Na2Ti3O7 phases. The lithium storage properties are evaluated in lithium-ion cells vs. lithium metal anode and titanate electrodes fabricated with PVDF and carboxymethyl cellulose (CMC) binders. The Li-storage by nanowires proceeds by a hybrid capacitive-diffusive mechanism between 0.1 and 2.5 V, which enables to achieve a high specific capacity. Sodium titanates accommodate Li+ by formation of mixed lithium-sodium-phase Na2−xLixTi6O13, which is decomposed to the distinct lithium phases Li0.54Ti2.86O6 and Li0.5TiO2. Contrary to lithium, the sodium storage is accomplished mainly by the capacitive reactions, and thus the phase composition is preserved during cycling in sodium ion cells. The isolated nanowires outperform bundled nanowires with respect to rate capability. [ABSTRACT FROM AUTHOR]

The results of comparative studies of the effect of current density on the average discharge voltage and specific discharge capacity of carbon electrodes based on heat-treated petroleum coke and graphite are presented. The carbon obtained by heat treatment of petroleum coke is shown to have better kinetic characteristics than graphite. The increase in the current density from 0.2 mA/cm2 (36 mA/g) to 2 mA/cm2 (364 mA/g) leads to a decrease in the discharge capacity of heat-treated petroleum coke by 26%; graphite, by 93%. When the current density is restored to 0.2 mA/cm2, the discharge capacity of carbon electrodes is also restored to its initial value. The increase in the current density is also shown to lead to increase in the average discharge voltage of lithium–carbon cells. Thus, with the increase in current density from 0.2 to 2 mA/cm2, the average discharge voltage of the lithium–carbon cells with the electrode active component of the heat-treated petroleum coke increased from 0.39 to 0.62 V; that of graphite, from 0.14 to 0.35 V. [ABSTRACT FROM AUTHOR]

CuCrO2 nanocrystals were synthesized and fabricated into mesoporous thin films to study their electrochemical properties, where a strong [Li+] dependence was observed. An anodic shift in the Cu2+/+ redox potential was observed with increased [Li+] in the electrolyte, in addition to the growth of a new redox feature at E1/2=−0.43 V vs Fc+/0. This new feature was attributed to Cu2+/+ redox chemistry accompanied by Li+ occupation in copper vacancy surface defects. The equilibrium constant and maximum charge for Li+ occupation were determined to be K=0.057 M−1 and 15.5 mC, respectively. The maximum charge was close to the expected value of 11 mC based on the measured concentration of copper vacancies. The pronounced Li+ dependent electrochemistry suggests that CuCrO2 behaves similarly to cathodes in Li‐ion batteries. Thus, chronopotentiometry experiments revealed a 7.8 mA h g−1 charge capacity at cycle 2 and increasing cycling efficiency from 83 to 91 % over 10 cycles. However, a pronounced decrease in charge capacity was observed with increased cycles, attributed to a loss in lithium‐coupled electrochemistry. These studies add to our understanding of surface defects in p‐type oxides and their effect on hole recombination in solar cell devices. [ABSTRACT FROM AUTHOR]

Lithium–manganese–oxide (Li-Mn-O) spinel is among the promising and economically viable, high-energy density cathode materials for enhancing the performance of lithium-ion batteries. However, its commercialization is hindered by its poor cyclic performance. In computational modelling, pivotal in-depth understanding of material behaviour and properties is sizably propelled by advancements in computational methods. Hence, the current work compares traditional DFT (CASTEP) and linear-scaling DFT (ONETEP) in a LiMn2O4 electronic property study to pave way for large-scale DFT calculations in a quest to improve its electrochemical properties. The metallic behaviour of LixMn2O4 (0.25 ≤ x ≤ 1) and Li2Mn2O4 was correctly determined by both CASTEP and ONETEP code in line with experiments. Furthermore, OCV during the discharge cycle deduced by both codes is in good accordance and is between 5 V and 2.5 V in the composition range of 0 ≤ x ≤ 1. Moreover, the scaling of the ONETEP code was performed at South Africa's CHPC to provide guidelines on more productive large-scale ONETEP runs. Substantial total computing time can be saved by systematically adding the number of processors with the growing structure size. The study also substantiates that true linear scaling of the ONETEP code is achieved by a systematic truncation of the density kernel. [ABSTRACT FROM AUTHOR]

Existence of van der Waals gaps renders two‐dimensional (2D) materials ideal passages of lithium for being used as anode materials. However, the requirement of good conductivity significantly limits the choice of 2D candidates. So far, only graphite is satisfying due to its relatively high conductivity. Recently, a new polymorph of layered germanium selenide (γ‐GeSe) was proven to be semimetal in its bulk phase with a higher conductivity than graphite while its monolayer behaves semiconducting. In this work, by using first‐principles calculations, the possibility was investigated of using this new group‐IV monochalcogenide, γ‐GeSe, as anode in Li‐ion batteries (LIBs). The studies revealed that the Li atom would form an ionic adsorption with adjacent selenium atoms at the hollow site and exist in cationic state (lost 0.89 e to γ‐GeSe). Results of climbing image‐nudged elastic band showed the diffusion barrier of Li was 0.21 eV in the monolayer limit, which could activate a relatively fast diffusion even at room temperature on the γ‐GeSe surface. The calculated theoretical average voltages ranged from 0.071 to 0.015 V at different stoichiometry of LixGeSe with minor volume variation, suggesting its potential application as anode of LIBs. The predicted moderate binding energy, a low open‐circuit voltage (comparable to graphite), and a fast motion of Li suggested that γ‐GeSe nanosheet could be chemically exfoliated via Li intercalation and is a promising candidate as the anode material for LIBs. [ABSTRACT FROM AUTHOR]

The bottleneck in the implementation of hybrid lithium-sodium-ion batteries is the lack of anode materials with a desired rate capability. Herein, we provide an in-depth examination of the Li-storage performance of sodium titanate nanowires as negative electrodes in hybrid Li,Na-ion batteries. Titanate nanowires were prepared by a simple and reproducible hydrothermal method. At a low reaction pressure, the well-isolated nanowires are formed, while by increasing the reaction pressure from 2 to 30 bar, the isolated nanowires tend to bundle. In nanowires, the local coordinations of Na and Ti atoms deviate from those in Na2Ti3O7 and Na2Ti6O13 and slightly depend on the reaction pressure. During the annealing at 350 °C, both Na and Ti coordinations undergo further changes. The nanowires are highly defective, and they easily crystallize into Na2Ti6O13 and Na2Ti3O7 phases. The lithium storage properties are evaluated in lithium-ion cells vs. lithium metal anode and titanate electrodes fabricated with PVDF and carboxymethyl cellulose (CMC) binders. The Li-storage by nanowires proceeds by a hybrid capacitive-diffusive mechanism between 0.1 and 2.5 V, which enables to achieve a high specific capacity. Sodium titanates accommodate Li+ by formation of mixed lithium-sodium-phase Na2−xLixTi6O13, which is decomposed to the distinct lithium phases Li0.54Ti2.86O6 and Li0.5TiO2. Contrary to lithium, the sodium storage is accomplished mainly by the capacitive reactions, and thus the phase composition is preserved during cycling in sodium ion cells. The isolated nanowires outperform bundled nanowires with respect to rate capability.

Phase transitions of two-dimensional nanomaterials and their heterostructures enable many applications including electrochemical energy storage, catalysis, and memory; however, the nucleation pathways by which these transitions proceed remain underexplored, prohibiting engineering control for these applications. Here, we demonstrate that the lithium intercalation-induced 2H-1T′ phase transition in MoS2 nanosheets proceeds via nucleation of the 1T′ phase at an atomically thin heterointerface by monitoring the phase transition of MoS2/graphene and MoS2/hexagonal boron nitride (hBN) heterostructures with Raman spectroscopy in situ during intercalation. We observe that graphene–MoS2 heterointerfaces require an increase of 0.8 V in applied electrochemical potential to nucleate the 1T′ phase in MoS2 as compared to hBN–MoS2 heterointerfaces. The increased nucleation barrier at graphene–MoS2 heterointerfaces is due to the reduced charge transfer from lithium to MoS2 at the heterointerface as lithium also dopes graphene based on ab initio calculations. Furthermore, we show that the growth of the 1T′ domain propagates along the heterointerface rather than through the interior of MoS2. Our results provide the first experimental observations of the heterogeneous nucleation and growth of intercalation-induced phase transitions in two-dimensional nanomaterials and heterointerface effects on their phase transitions. These insights have implications for the design of energy technologies and devices that rely upon the phase stability of nanostructured materials. [ABSTRACT FROM AUTHOR]

The charging and discharge characteristics of electrodes based on LiNi0.8Co0.15Al0.05O2 (NCA) and Li4Ti5O12 (LTO) are studied in LiClO4 solutions in a mixture of propylene carbonate and dimethoxyethane at the temperature from –45 to +60°С. For both materials, the discharge capacity decreases with the current increase and its dependence cannot be described by the Peukert equation. The decrease in the temperature results also in the increase in polarization, the effective energy of activation being 52 kJ/mol on the NCA electrode and only 23 kJ/mol on the LTO electrode. The possibility of using batteries based on the NCA–LTO system at the temperature down to –40°С is confirmed. [ABSTRACT FROM AUTHOR]

The realizing of new electrode materials and the modification of existing ones are important trends in the development of lithium-ion batteries. Of particular importance is the assessment of their diffusion ability, that is, the ability to provide transport of the electroactive component. For this purpose, electrochemical methods such as cyclic voltammetry, electrochemical impedance spectroscopy, potentiostatic intermittent titration, and galvanostatic intermittent titration techniques are used. The chemical diffusion coefficient D estimated in such electrode materials is shown to have a spread in values by several orders of magnitude. The main reasons for this rather significant dispersion are discussed, including the uncertainty of the estimates of the diffusion surface area and the using of various approaches to the obtaining of equations for the calculating of D. The conclusions are illustrated by examples of the D estimates in LixC6-, LixSn-, LixTiO2-, LixWO3-, LiMyMn2 –yO4-, and LiFePO4-based electrode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D multilayered Ti 3 C 2 T x MXene adsorbents were fabricated via selective Al element etching. • Li+-intercalation increased the interlayer spacing and surface area. • TCF-2 exhibited broad working pH range and excellent Nd3+ adsorption capacity (517.8 mg/g). • The Nd3+/Fe3+ selectivity of TCF-2 reached 221. • The adsorption mechanism was elucidated using different characterizations. Recovering rare earth elements (REEs) from low-concentration REE-bearing waste streams has been deemed as a sustainable approach to diversity REE supply and reduce environmental burden. However, highly selective separation of trivalent Fe3+ and Al3+ impurities during low-concentration REE processing still remains a critical challenge. In this study, two-dimensional multilayered MXene adsorbents TCFs were successfully prepared and utilized for Nd3+ adsorption via selective etching of Al element in Ti 3 AlC 2. It was found that LiF/HCl-etched TCF-2 can simultaneously realize effective Al etching, interlayer spacing expansion and in-situ Li+ intercalation. The intercalated Li+ amount was up to 4.44 wt% (6.40 mmol/g). Compared with HF-etched TCF-1, TCF-2 demonstrated boosted adsorption kinetics (2 h), large adsorption capacity (517.79 mg/g), impressively high selectivity (Nd3+/Fe3+ SF = 221, Nd3+/Ca2+ SF = 858, Nd3+/Mg2+ SF = 3545), and broad working pH range (2–7). Various experimental characterizations reveal that selective Nd3+ recovery is owing to the ion-exchange and surface complexation induced by interlayer Ti-O/Ti-OH of TCF-2. Specifically, the extended X-ray sorption fine structure (EXAFS) results, in combination with density functional theory (DFT) calculations, further confirm the Nd3+ is selectively adsorbed by forming surfaced complexes structure in the interlayer. And this is also evidenced by the decrease of Nd-O distances and high coordination number. The present results illustrate that alkaline metal ion-intercalated MXene could serve as a promising candidate to efficiently remove trivalent Fe3+ impurities for REEs recovery. [ABSTRACT FROM AUTHOR]

Developing bifunctional catalysts for both hydrogen and oxygen evolution reactions is a promising approach to the practical implementation of electrocatalytic water splitting. However, most of the reported bifunctional catalysts are only applicable to alkaline electrolyzer, although a few are effective in acidic or neutral media that appeals more to industrial applications. Here, a lithium‐intercalated iridium diselenide (Li‐IrSe2) is developed that outperformed other reported catalysts toward overall water splitting in both acidic and neutral environments. Li intercalation activated the inert pristine IrSe2 via bringing high porosities and abundant Se vacancies for efficient hydrogen and oxygen evolution reactions. When Li‐IrSe2 was assembled into two‐electrode electrolyzers for overall water splitting, the cell voltages at 10 mA cm−2 were 1.44 and 1.50 V under pH 0 and 7, respectively, being record‐low values in both conditions. [ABSTRACT FROM AUTHOR]

Lithium ion (Li+) aggregation in the amorphous tungsten oxide (a-WO x) film is the main cause of the electrochromic (EC) device failure. This has hindered a-WO x films goes towards industrialization on behalf of the giant EC performance and long-term reliability. A novel kind of electrolytes consisted of Aluminum ions (Al3+) and Lithium ions (Li+) used for electrochromic sputtered a-WO x films is presented. With the newly designed Al3+/Li+ co-existed electrolytes, the optical transmittance modulation can be largely enhanced compared with Li+, meanwhile, the problem of degradation after long-term cycling for a-WO x induced by Li ions-trapping is able to be solved. Furthermore, the utilization of Al3+ brings slow switching kinetics at the ions extraction step to the films compared with Li+, which supplies a new method to modulate the bleaching rate by applying adjustable Al3+/Li+ ratio of electrolytes and a tunable and controllable switching time is easily achieved in this work. This Al3+/Li+ co-based electrolyte opens a new way to design and control the high contrast, long-lived cycling stability and changeable switching time EC devices based on a-WO x films. [ABSTRACT FROM AUTHOR]

The V2O5 thin films has been widely studied because it has application as ionic host in electrochromic and lithium-ion batteries, two technologies that have an intimate connection with sustainability as substitutes for fossil energies and as agents for improving energy efficiency. In electrochromic technology, V2O5 is applied as a passive electrode due to its high transmittance and small contrast, and its reversibility on electrochemical reactions. To contribute to increase the optical and charge efficiency of V2O5 thin film passive electrodes, were investigated in this work the influence of the morphological properties, crystallite size and roughness, on the reversible specific charge capacity and the respective optical responses. The films morphological properties were modified by varying their thickness to the nanoscale. The films were deposited by thermal evaporation from powdered V2O5. The crystallite size and surface roughness were measured respectively by XRD and AFM. The results showed that the charge capacity is directly proportional to the surface roughness and inversely proportional to the crystallite size. The film optical contrast and the nominal transmittance shows to be improved according to their morphological properties. In conclusion, the V2O5 opto-electrochemical properties can be improved, increasing the efficiency on the light control processes.

Penetration of sodium into carbon-graphite material (CGM) specimens previously modified with lithium is studied. Sodium diffusion coefficients are calculated after treating CGM with lithium vapor and values are determined for activation energy of diffusion under different conditions. The kinetic dependences obtained make it possible to determine the sodium diffusion mechanism in modified CGM. The efficiency is demonstrated of preliminary treatment with lithium vapor that makes it possible to prevent aluminum electrolyzer cathode lining surface layer breakdown during operation. The tests on CGM specimens performed make it possible to create prerequisites for developing technology for hearth surface protection from sodium penetration during electrolysis in molten cryolite-alumina. [ABSTRACT FROM AUTHOR]

Herein, we reported a facile method to synthesize the nanostructured vanadium oxides by electrochemical deposition, followed by thermal treatment. Polymer surfactant was selected as a template agent to control the nanostructures. Nanorod-, nanoparticle- and platelet-structured vanadium oxides with different sizes were obtained by simply changing the surfactant concentrations. The crystallinity of various nanostructured vanadium oxide was confirmed by X-ray diffraction. X-ray photoelectron spectroscopic analysis reveals a mixed valence nature of vanadium specie in which the amount of V(V) and V(IV) species is not significantly affected by varying the surfactant concentrations. Cyclic-voltammetry curves show that the smallest potential separation between the cathodic and anodic peaks for the nanorod-structured vanadium oxide. The nanorod-structured vanadium oxide exhibits excellent Li-ion intercalation properties, much better than that of the nanoparticle- and platelet-structured vanadium oxides. Thus, the excellent performance with low-cost make the nanorod-structured vanadium oxide promising potential as a cathode material for the Li-ion battery applications. [ABSTRACT FROM AUTHOR]

The problem of hardening (increasing the stability) of the carbon graphite hearth lining for protection against diffusion of sodium and cryolite-alumina melt (CAM) is discussed. Analytical evaluation showed that the main protection against various kinds of electrolyte effects on the carbon graphite lining is the application of various coatings that have not found wide industrial application due to their failure. It was demonstrated that the addition of lithium to the cryolite-alumina melts has a positive effect on the properties of the carbon graphite hearth lining. It was established that lithium has an active influence on the change in the physical and operational properties of the lining as a result of the intercalation process. The improvement in the properties of the carbon graphite electrolysis cell lining was confirmed by a series of experimental studies carried out with lithium electrolytes. [ABSTRACT FROM AUTHOR]

The creation of new environmentally friendly and portable energy sources requires the development of technology used to produce lithium-ion batteries, especially their anodes. The aim of this study was to show the possibilities of the state-of-the-art ab initio approach for modeling battery anode materials. A quantum-mechanical study of the limiting filling of a silicene/aluminum anode with lithium has been performed. In this case, the changes in the structure, energy, and electronic properties of silicene that occur upon filling the anode have been studied. Lithium atoms are deposited both inside and on top of the channel formed by two parallel silicene sheets. The ratio of lithium to silicon varies in the range of 0.1–1.5. The gap in the silicene channel increases as the channel is filled with lithium. The filling of the silicene channel with lithium is associated with an increase in the Si–Si bond length in both silicene sheets without destruction of the channel. The infiltration of lithium into the space between the aluminum substrate and silicene sheet has been determined. Our calculation of the band structure has shown that, regardless of filling with lithium, the silicene-aluminum system exhibits metallic conductivity. The storage capacity of the combined anode (729 mAh g−1) significantly exceeds the capacity of graphite anodes. It was found that the top sheet of silicene acquires a negative electric charge upon significant lithium filling of the anode, exceeding the absolute value of the negative charge of the bottom sheet in contact with the aluminum substrate. Therefore, our model study has elucidated that the new silicene-aluminum anode is a promising material for the creation of a new generation of lithium-ion batteries. • The limiting filling of silicene/aluminum anode with lithium first investigated. • Ab initio molecular dynamics calculations were performed at 293 K. • The new result is a calculated capacity (729 mAh g−1) of the silicene/Al anode. • The silicene-Al system exhibits metallic conductivity even in the absence of Li. [ABSTRACT FROM AUTHOR]

Undoped and Cu-doped CeO (2.5, 5, 7.5 mol%) thin films were prepared by modified Pechini process. Grazing incidence X-ray diffraction investigations of the films revealed that the ceria thin film has a cubic structure and Cu doping inhibited the crystal growth. The presence of predominant of Ce oxidation state (CeO) and Cu in the films was approved by X-ray photoelectron spectroscopy. The fourier transform infrared spectra confirmed the metal-oxygen (Ce-O) bonding. Scanning electron microscopy images of the films displayed a crack free surface and the nano-grains regularly distributed on the surface. Atomic force microscopy analyses indicated that roughness parameters changed by Cu incorporation and 5 mol% Cu-doped CeO is the smoothest surface. Fractal dimensions of surface were calculated by box counting and triangulation method. The fractal dimension increased by Cu doping up to 5 mol% and then reduced. The optical transmittance was enhanced and the absorption edge was shifted to lower wavelength by Cu doping. The refractive indices and extinction coefficients which were determined using theoretical approach were decreased by Cu doping. Photoluminescence emission intensity of CeO thin film was quenched by Cu doping. The electrochemical behavior of the films was examined in 1 M LiClO/propylene carbonate electrolyte. The total charge density of ceria thin film increased by Cu doping and 5 mol% Cu-doped CeO film had the highest ion storage capacitance. The fractal analyses showed that the surface morphology affected the Li ion diffusion behavior of CeO:Cu thin films. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The adsorption of CO 2 and H 2 O on divacanacy (DV) defected graphene cluster, and its bilayer counterpart is investigated using first-principles calculations. Both single and bilayer DV graphene cluster, are functionalised with H and F atoms. On these sheets the gas molecules are physisorbed, and the divacancy defect effectively improves the adsorption of CO 2 , while fluorination enhances the hydrophobicity of the graphene cluster. Among the convex and concave curvature regions induced due to the DV defect, the adsorption of the gas molecules on the concave meniscus is more favourable. Fluorine termination induces 73% reduction in Henry law constants for H 2 O, while for the CO 2 molecule it increases by 8%, which indicates the DV defective sheet is a better candidate for CO 2 capture compared to the STW defective sheet. Besides, both AA and AB divacant defect bilayer sheets are equally stable, wherein AA stacking results in a cavity between the sheets, while in AB stacking, the layers slide one over the other. Nevertheless, both these bilayer sheets are comparatively stabler than the monolayer. However, intercalation of lithium decreases the interlayer separation, particularly in AA stacking, which enhances the CO 2 adsorption, but in the Bernal stacking enhances it hydrophobicity. [ABSTRACT FROM AUTHOR]

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 LiCo 0.415 Mn 0.435 Ni 0.15 O 2 . 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 LiNO 3 and NaNO 3 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. [ABSTRACT FROM AUTHOR]

In this work, lithium plating is investigated by means of voltage relaxation and in situ neutron diffraction in commercial lithium-ion batteries. We can directly correlate the voltage curve after the lithium plating with the ongoing phase transformation from LiC 12 to LiC 6 according to the neutron diffraction data during the relaxation. Above a threshold current of C/2 at a temperature of −2 °C, lithium plating increases dramatically. The results indicate that the intercalation rate of deposited lithium seems to be constant, independent of the deposited amount. It can be observed that the amount of plating correlates with the charging rate, whereas a charging current of C/2 leads to a deposited amount of lithium of 5.5% of the charge capacity and a current of 1C to 9.0%. [ABSTRACT FROM AUTHOR]

LiNbO 3 -coated LiNi 0.5 Mn 1.5 O 4 powders were synthesized by a sol–gel method, and their intercalation property as a cathode material was investigated using all-solid-state batteries with Li 10 GeP 2 S 12 solid electrolyte and In–Li metal anode. The LiNbO 3 coating delivered reversible lithium intercalation of LiNi 0.5 Mn 1.5 O 4 through an electrochemical interface with the Li 10 GeP 2 S 12 . Oxygen-deficient LiNi 0.5 Mn 1.5 O 4 − δ with a higher electronic conductivity than LiNi 0.5 Mn 1.5 O 4 improved the intercalation activity. An all-solid-state battery consisting of 3 wt.%-LiNbO 3 -coated LiNi 0.5 Mn 1.5 O 4− δ /Li 10 GeP 2 S 12 /In–Li exhibited a discharge capacity of 80 mAh g − 1 at the first cycle with an average discharge voltage of 4.1 V (vs. In-Li), which demonstrates the possibility of 5 V class all-solid-state batteries with a high voltage spinel cathode. [ABSTRACT FROM AUTHOR]

Materials based on layered LiVO 2 are mostly considered as a potential anodes for Li-ion batteries, competitive to commonly used graphite. They can also act as cathode materials, however there are almost no studies on this subject. LiVO 2 and it delithiated derivatives were widely studied during 80s and 90s of the 20th century mainly because of its magnetic properties. This work presents evaluation of crystal structure, oxygen nonstoichiometry, transport and electrochemical properties of Li(Li y Fe z V 1 − y − z )O 2 − δ group of materials, with special insight to their possible application as cathode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

A high concentration of lithium, corresponding to charge capacity of ∼4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles. The present work argues that the hollow spherical geometry alone cannot ensure the absence of fracture. Using classical molecular dynamics and density functional theory based simulations; satisfactory explanation to the absence of fracture has been explored at the atomic scale. [ABSTRACT FROM AUTHOR]

Thin films of V2O5 xerogel were characterized by several in-situ techniques for different amount of intercalated Li+. Changes in the V2O5 mechanical properties were analyzed by electroacoustic impedance data, indicating that lithium intercalation does not produce an important change in the viscoelastic properties. So that, it is possible to use the electrochemical quartz crystal microbalance to measure mass change. Electrogravimetric results showed a significant participation of propylene carbonate molecules during charge/discharge cycles, associated with a significant expansion/contraction of the structure. The ultraviolet-visible spectrophotometry, chronoamperometry and electrochemical impedance spectroscopy data showed the influence of structural modifications on electronic and ionic properties during the intercalation process. The amorphization of the material in the discharged state produces a diminution in the charge carrier rate. Besides this, changes in the local symmetry of the vanadium ion by extended X-ray absorption fine structure experiments, were verified.

Keywords: CuCrO2; CuGaO2; delafossite; lithium intercalation; p-type metal oxide EN CuCrO2 CuGaO2 delafossite lithium intercalation p-type metal oxide 1 1 1 12/15/22 20221213 NES 221213 B The Cover Feature b illustrates lithium-coupled redox reactions between Cu SP 2+ sp and Cu SP + sp at the surface of CuCrO SB 2 sb delafossite nanocrystals. The lithium-coupled redox activity is the result of copper vacancy defects at the nanocrystal surface where Li-ions occupy vacant sites in the reduced state and return to solution in the oxidized state. CuCrO2, CuGaO2, delafossite, lithium intercalation, p-type metal oxide. [Extracted from the article]

Graphite anode behaviour is of great interest for the optimization of Lithium-ion batteries. The improvement of battery performance depends on an understanding of lithium intercalation/de-intercalation in graphite anodes, especially in regards to energy and power density. In this study we present a new approach for investigating graphite anode behaviour under equilbirum and nonequlibirum conditions. It is based on reflectance change measurements from a graphite anode surface, relative to state of charge (SOC). We have introduced an innovative optical test cell and used a photodiode. A reflectance change hysteresis occurs between lithium intercalation and de-intercalation, under equilbrium conditions. This was ascribed to specific lithium-carbon bonds at the graphite particle edge region. Charging and discharging have a unique reflectance change characteristic. This was assigned to SOC nonequilibrium in the anode and serves as clear evidence that limited lithium mobility in the porous microstructure is a signficant loss factor. We then performed a more detailed analysis of the anode loss processes by correlating the anode reflectance change with dynamic electrical excitation. This method, Optical Impedance Spectroscopy (OIS), provided detailed information about the frequency range of the loss processes. It also confirmed our assigning the low frequency range (1 mHz-3 Hz) to solid state diffusion and lithium transport in the electrolyte filled pores. The results are in excellent agreement with previous EIS studies. We conclude that OIS is applicable for validating physicaly-based graphite anode models and determining model parameters, in combination with EIS. [ABSTRACT FROM AUTHOR]

TiS2/Li10GeP2S12 composite electrodes were fabricated using a mill pot rotator, and their electrochemical properties were investigated with all solid-state batteries of TiS2/Li10GeP2S12/In-Li. The batteries compressed under 19 MPa showed poor cycle stability and low rate capability due to deterioration of physical contact between the TiS2 electrode and the Li10GeP2S12 solid-electrolyte. The battery performance was much improved by applying a pressure of 230 MPa throughout the electrochemical cycling. The battery delivered the reversible capacity of over 160 mAh g-1 with high retention under 1 C operation condition. [ABSTRACT FROM AUTHOR]

Chemical intercalation of lithium in single crystals of TiX2 (X=S, Se, Te) was studied at pressures of 10-500 MPa and temperatures of 293-363 K. Crystals were synthesized by chemical vapor synthesis and cut with a LASER into squares (2.2 ? 2.2mm). Samples and 1.6mol · L-1 n-butyl lithium solutions in n-hexane (BuLi) were sealed in gold capsules. Experiments were carried out in cold seal pressure vessels for 5-20 days using Ar as pressure medium. A large fraction of samples showed degradation after the experiments, i.e., at low pressures and at high temperatures. On samples withminor degradation, lithium profiles weremeasured parallel to the crystallographic ab-plane, using femtosecond- LASER Ablation-Inductively Coupled Plasma-Optical Emission Spectroscopy and -Mass Spectrometry (fs-LA-ICP-OES and -MS). Most of the profiles could be well fitted by the specific solution of Fick's second law for the given boundary conditions. Lithium diffusivities (x Li) and lithium contents at the crystal edges (xLi,S) were determined from the fits. At 500 MPa and roomtemperature lithiumdiffusivities are similar in TiS2 ((1.07 to 2.41) ?10-15 m² · s-1) and TiSe2 ((1.48 to 2.10) ?10-15 m² · s-1) but significantly lower in TiTe 2 ((0.07 to 0.55) ?10-15 m² · s-1). Moreover, diffusivity of Li in TiTe 2 decreases significantly with increasing pressure whereas for the other chalcogenides a pressure dependence cannot be evidenced. Lithium surface contents are lower for TiS2 (x = 0.15 to 0.36) than for TiSe2 (0.66 to 0.71) and TiTe2 (0.59 to 0.99), slightly elevated compared to ambient pressure experiments. These findings indicate, that the ionicity of the Ti-X bonding as well as the size of the interlayer space (van der Waals gap) play a crucial role for the degree of lithium insertion and for the pressure dependence of lithium diffusivity. [ABSTRACT FROM AUTHOR]

We test the stability of pre-lithiated graphite anodes for Li-ion batteries in a dry room battery processing room. The reaction between LiC x and laboratory air was followed using operando NMR and x-ray diffraction, as these methods are sensitive to change in Li stoichiometry in graphite. There is minimal reactivity between LiC 6 and N 2 , CO 2 or O 2 ; however, LiC 6 reacts with moisture to form lithium (hydr)oxide. The reaction rate follows zero-order kinetics with respects to intercalated lithium suggesting that lithium transport through the graphite is fast. The reaction occurs by sequential formation of higher stages–LiC 12 , then LiC 18 , and then LiC 24 –as the hydrolysis proceeds to the formation of Li x OH y and graphite end products. Slowing down the formation rate of the Li x OH y passivation layer stabilizes of the higher stages. [ABSTRACT FROM AUTHOR]

LiFePO4 is a promising phase-separating battery electrode and a model system for studying lithiation. The role of particle synthesis and the corresponding particle morphology on the nanoscale insertion and migration of Li is not well understood, and elucidating the intercalation pathway is crucial toward improving battery performance. A synchrotron operando liquid X-ray imaging platform is developed to track the migration of Li in LiFePO4 electrodes with single-particle sensitivity. Lithiation is tracked in two particle types-ellipsoidal and platelet-while the particles cycle in an organic liquid electrolyte, and the results show a clear dichotomy in the intercalation pathway. The ellipsoidal particles intercalate sequentially, concentrating the current in a small number of actively intercalating particles. At the same cycling rate, platelet particles intercalate simultaneously, leading to a significantly more uniform current distribution. Assuming that the particles intercalate through a single-phase pathway, it is proposed that the two particle types exhibit different surface properties, a result of different synthesis procedures, which affect the surface reactivity of LiFePO4. Alternatively, if the particles intercalate through nucleation and growth, the larger size of platelet particles may account for the dichotomy. Beyond providing particle engineering insights, the operando microscopy platform enables new opportunities for nanoscale chemical imaging of liquid-based electrochemical systems. [ABSTRACT FROM AUTHOR]

The electrochemical reaction with lithium of a vanadium-based metal-organic framework V IV (O)(bdc) [MIL-47], which is isostructural to the iron compound MIL-53(Fe), was investigated. The large open channels which can accommodate small guest species, such as Li + ions, together with the redox properties of the tetravalent vanadium ions make this material of potential interest as a rechargeable intercalation electrode for lithium batteries. The electrochemical properties were investigated in Li|1 M LiPF 6 in ethylene carbonate (EC) and dimethyl carbonate (DMC)|V(O)(bdc) cells between 4.0 and 1.5 V vs. Li/Li + . V(O)(bdc) cathodes can be reversibly cycled in Li cells with good rate capability and specific capacity. At a current density of C /12, Li/V(O)(bdc) cells can be cycled between 0 ≤ x ≤ 0.7 in Li x V(O)(bdc) with ∼100% coulombic efficiency corresponding to 82 mAh g −1 which is a higher capacity than that found for MIL-53(Fe). The cell performance and electrochemical profiles at various current conditions are discussed. Structural evolution taking place during lithium intercalation was monitored by powder X-ray diffraction on phases of Li x V(O)(bdc) (0 < x ≤ 2) chemically prepared by using n-BuLi. Previous studies of the reaction of lithium with metal-organic frameworks are briefly reviewed for comparison with the data presented for Li x V(O)(bdc). [ABSTRACT FROM AUTHOR]

A lithium-assisted approach has been developed for the exfoliation of pristine graphite, which allows the large-scale preparation of few-layer graphene nanosheets. The process involves an unexpected physical insertion and exfoliation, and the graphene nanosheets prepared by this method reveal undisturbed sp-hybridized structures. A possible two-step mechanism, which involves the negative charge being trapped around the edges of the graphite layers and a subsequent lithiation process, is proposed to explain the insertion of lithium inside the graphite interlayers. If necessary, the present exfoliation can be repeated and thinner (single or 2-3 layer) graphene can be achieved on a large scale. This simple process provides an efficient process for the exfoliation of pristine graphite, which might promote the future applications of graphene. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Lithium insertion in FeNb 2 O 6 and CrNb 2 O 6 has been investigated using the galvanostatic charge–discharge method and showed that more than half of the intercalated Li + during first cycle is retained in the structure and is not de-intercalated during subsequent cycles. The effects of sintering on FeNb 2 O 6 were investigated with lower applied temperatures yielding higher Li + intercalation capability. Post galvanostatic XRD shows that the initial phase has been retained during cell cycling. Cyclic voltammetry reveals that chromium also takes part in electro-chemical activity in CrNb 2 O 6 . [ABSTRACT FROM AUTHOR]

Calcium manganate Ruddlesden–Popper phases Ca 2 MnO 4–δ were prepared by soft chemistry and treated with acid to extract a part of the calcium ions. Combined structural, morphological and spectroscopic analyses by XRD, SEM/EDX, TEM and Raman revealed an amorphization of the treated surface with a preserved inner crystalline phase in the core of the particles. The inner part of the particles consists of Ca 2 MnO 4–δ and the outer part of hydrated amorphous manganese oxide MnO 2 ·xH 2 O. Although pristine Ca 2 MnO 4–δ is not electrochemically active, electrochemical characterization of the acid-treated powders shows a significant change in capacity that correlates to the amount of extracted calcium. The cycling stability of the Ca 2 + extracted compounds was improved by more than a factor of 10 in comparison to pure MnO 2 ·xH 2 O. The acid-treated Ca 2 MnO 4–δ showed enhanced capacity retention of up to 50% after 70 cycles compared to 4% for bare MnO 2 ·xH 2 O due to its crystalline core. [ABSTRACT FROM AUTHOR]

Recently, layered Li1+xV1−xO2 with x≥0 has attracted significant attention as an anode material for Li-ion batteries. Its high volumetric and gravimetric capacities (1360mAh·cm−3 and 300mAh·g−1 respectively) make it particularly interesting. During lithium intercalation Li1+xV1−xO2 with x>0 exhibits wide potential plateau below 0.1V vs. Li/Li+, while for stoichiometric LiVO2 lithium uptake hardly occurs. In this work evaluation of crystal structure, transport and electrochemical properties is given for Li1+xV1−xO2 materials with x=0, 0.03 and 0.07. Li1+xV1−xO2 showed activated character of conductivity with activation energy about 0.2–0.3eV. Thermoelectric power values exceeding 80μV·K−1 point to electron holes as the main charge carriers. Thermogravimetric measurements carried out in air indicated only minor variations of mass of the materials up to 215°C, suggesting high stability along with low level of oxygen nonstoichiometry. [ABSTRACT FROM AUTHOR]

New data on the structure and reversible lithium intercalation properties of sodium-deficient nickel-manganese oxides are provided. Novel properties of oxides determine their potential for direct use as cathode materials in lithium-ion batteries. The studies are focused on NaNiMnO with x = 2/3. Between 500 and 700 °C, new layered oxides NaNiMnO with P3-type structure are obtained by a simple precursor method that consists in thermal decomposition of mixed sodium-nickel-manganese acetate salts obtained by freeze-drying. The structure, morphology, and oxidation state of nickel and manganese ions of NaNiMnO are determined by powder X-ray diffraction, SEM and TEM analysis, and X-ray photoelectron spectroscopy (XPS). The lithium intercalation in NaNiMnO is carried out in model two-electrode lithium cells of the type Li|LiPF(EC:DMC)|NaNiMnO. A new structural feature of NaNiMnO as compared with well-known O3-NaNiMnO and P2-NaNiMnO is the development of layer stacking ensuring prismatic site occupancy for Na ions with shared face on one side and shared edges on the other side with surrounding Ni/MnO octahedra. The reversible lithium intercalation in NaNiMnO is demonstrated and discussed. [ABSTRACT FROM AUTHOR]

Influence of the ultrasound on talc (Mg 3 Si 4 O 10 (OH) 2 ) cathode material was experimentally investigated. The Gibbs׳ energy change of the Li + - intercalation process, the diffusion coefficient in Li x Mg 3 Si 4 O 10 (OH) 2 , the charge transfer resistance and the capacitance of the electric double layer were studied in electrochemical cells, based on initial and ultrasonic treated talc. The obtained results were interpreted within the nonlinear diffusion-deformation model, which involved formation of vacancy nanoclusters under ultrasonic influence at temperatures lower than a critical value. [ABSTRACT FROM AUTHOR]

Abstract: Lithium battery performances degrade even at rest time that means when electric/hybrid electric vehicles are in the parking. This phenomenon is well known as calendar aging. In this paper, the kinetic of the CC–CV charge at 1 C and mainly kinetic of the voltage regulation, CV step, is investigated as an indicator of battery state-of-health through calendar aging. In fact, CV step is responsible in a major part of lithium intercalation into negative electrode and revealed to give signification on cyclable lithium loss which is the major cause of calendar aging according to literature and post mortem analysis. Comparison from the aging of four battery technologies is presented. Through aging, results show a difference in battery behavior even if the time for CC charge is decreasing for all the battery. According to battery technology, the current during CV charge phase has been useful for lithium–nickel–manganese–cobalt-oxide, lithium–nickel–cobalt–aluminum-oxide and lithium-ion–manganese battery state-of-health determination. However, in the case of the lithium–iron–phosphate battery, simple calculation of the duration of the CV step revealed to be very accurate compared to the classic discharged capacity measurement. [Copyright &y& Elsevier]