Low Lithium Concentrations Research Articles

Fertility of Rare-Metal Peraluminous Granites and Formation Conditions of Tungsten Deposits

The tungsten distribution in rocks of the Kukulbei Complex in eastern Transbaikal region results in a high potential of rare-metal peraluminous granites (RPG) for W mineralization and displays a different behavior of W in Li–F and “standard” RPG. These subtypes differ in the behavior of W in melt, spatial localization of mineralization, and the timing of wolframite crystallization relative to the age of the parental granitic rocks. The significant of W concentration is assumed to be due to fractionation of the Li–F melt; however, wolframite mineralization in Li–F enriched granite is not typical in nature. The results of experiments and our calculations of W solubility in granitic melt show that wolframite hardly ever crystallizes directly from melt; it likely migrates in the fluid phase and is then removes from the magma chamber to the host rocks, where secondary concentration takes place in exocontact greisens and quartz–cassiterite–wolframite veins. At the same time, the isotopic age of accessory wolframite (139.5 ± 2.1 Ma) within the Orlovka massif of Li–F granite is close to the formation age of the massif (140.6 ± 2.9 Ma). A different W behavior is recorded in the RPG subtype with a low lithium and fluorine concentration, exemplified by the Spokoininsky massif. There is no significant W gain in the melt. All varieties of wolframite mineralization in the Spokoininsky massif are derived from greisens, veins, and pegmatoids yielding the same crystallization ages (139.5 ± 1.1 Ma), which are 0.9–1.8 Ma later (taking into account the mean-square weighted deviation) than the Spokoininsky granite formation (144.5 ± 1.4 Ma). Perhaps this period corresponds to the time of transition from the magmatic stage to hydrothermal alteration. Comparison of the isotope characteristics (Rb–Sr and Sm–Nd isotope systems) of rocks and the associated ore minerals (wolframite, cassiterite) from all examined deposits shows a depletion in eNd values for ore minerals relative to the rock and the opposite behavior for the intial Sr isotope ratios. This may indicate the specific nature of ore matter, where the effect of the juvenile component is definitely expressed. Our geochronological results show that tantalum and tungsten mineralization took place within a narrow age interval, almost synchronously with the crystallization of associated granites. The coeval development of peraluminous magmatism enriched in lithophile rare elements and volatiles with ore complexes located in different structural settings and separated by a considerable distance from each other (up to 500 km) suggests a regional and deep-seated magma source. Rifting and increased thermal flux from the mantle, manifestations of which have been recorded during this period in the territory, may be a deep-seated process.

An Experimental and First Principles Study of the Energetics of Lithium Insertion into Fe3O4 and γ-Fe2O3

Inverse spinel magnetite, Fe3O4, has been studied as an electrode material for lithium-ion batteries due to its low cost, high abundance, and low environmental impact.1 Experimental discharge profiles of Fe3O4 initially show a concentration dependent voltage profile. The lithium concentration range of that profile varies as a function of nanoparticle size, with smaller particles exhibiting a larger intercalation regime.2,3 Thackeray et al. proposed initial lithium intercalation into magnetite on 16c sites, where the lattice accommodates a critical concentration of lithium without significant structural rearrangements. Above a critical concentration of lithium, Thackeray et al. proposed that with further discharge, lithium insertion to 16c sites leads to Fe8a displacement to vacant 16c sites in the material.4 It is also known that magnetite is iron deficient, Fe3-δO4 in the bulk and in the nanoparticulate forms with vacancies on the octahedral 16d sites.5–7 The most drastic manifestation of this oxidation process is maghemite, with δ=1/3, the topotactic oxidative product written as (Fe1 3+)8a[Fe1.66 3+♦0.33]16dO4 with ♦ as a 16d iron defect, or γ-Fe2O3. Menard et al. showed that the defects in nanoparticulate magnetite increase with decreasing nanoparticle size, but a thorough investigation of how defects affect the electrochemistry is yet to be presented.2 Using DFT+U calculations, we have investigated lithium intercalation in Fe3O4 magnetite. Our results show that stoichiometric Fe3O4 is not an intercalation material, with no stable phases for the LixFe3O4 0<x<1 convex hull. Resultantly, a voltage plateau at approximately 2.0 V is predicted, corresponding to a continuous phase transformation from inverse spinel Fe3O4 to rock-salt LiFe3O4with Li and Fe occupying 16c sites. This rules out the original hypothesis for a critical concentration of lithium hosted on the 16c sites resulting in a concentration dependent voltage at low concentrations of lithium in magnetite. We have performed DFT+U calculations on lithiated Fe3-δO4 with δ=0,1/8, and 1/3 to understand how 16d iron defects affect the open circuit potential of magnetite and therefore the discharge behaviour. In the presence of 16d iron defects, we have found that even at low concentrations of lithium, insertion on vacant 16c sites causes significant Fe8a rearrangements. When lithium is inserted on 16c positions, its proximity to Fe8a induces Coulombic repulsion between the Li16c and the Fe8a, and the resultant material is thermodynamically unstable against phase segregation. On the other hand, when lithium is inserted on vacant 16d sites available in the δ=1/8 and 1/3 cases, a structurally stable intercalated material results and DFT+U predicted voltages align with experimental observation. We further hypothesize that the concentration of defects is a function of nanoparticle size. Then we are able to explain the experimentally observed size-dependent open circuit potential and the variation of discharge capacity with particle size in a natural way. Finally, with DFT+U calculations we are able to provide a mechanism for intercalation and phase-segregation that is consistent with the nanoparticle size dependence observed in the electrochemical experiments. This work was supported as part of the Center for Mesoscale Transport Properties, an Energy Frontier Research Center supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under award #DE-SC0012673. This research used resources of the Center for Functional Nanomaterials, a U.S. DOE Office of Science User Facility, at Brookhaven National Laboratory, Contract No. DE-SC0012704. The Extreme Science and Engineering Discovery Environment (XSEDE) was used, supported by National Science Foundation grant number ACI-1548562. The Yeti Shared HPC Cluster at Columbia University was used, which includes support from Empire State Development's Division of Science, Technology, and Innovation, contract number C090171. C. N. L. acknowledges the support of the National Science Foundation Graduate Research Fellowship under Grant No. DGE-11-44155. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. (1) Ito, S.; Nakaoka, K.; Kawamura, M.; Ui, K.; Fujimoto, K.; Koura, N. J. Power Sources 2005, 146, 319–322. (2) Menard, M. C.; Marschilok, A. C.; Takeuchi, K. J.; Takeuchi, E. S. Electrochim. Acta 2013, 94, 320–326. (3) Menard, M. C.; Takeuchi, K. J.; Marschilok, C.; Takeuchi, E. S. 2013, 15, 18539–18548. (4) Thackeray, M. M.; David, W. I. F.; Goodenough, J. B. Mater. Res. Bull. 1982, 17, 785–793. (5) Daniels, J. M.; Rosencwaig, a. J. Phys. Chem. Solids 1969, 30, 1561–1571. (6) Dieckmann, R. Berichte der Bunsen-Gesellschaft fur Phys. Chemie 1982, 86, 112–118. (7) Johnson, C. E.; Johnson, J. A.; Hah, H. Y.; Cole, M.; Gray, S.; Kolesnichenko, V.; Kucheryavy, P.; Goloverda, G. Hyperfine Interact. 2016, 237, 1–10.

Surface Sensitivity of Fluoroethylene Carbonate Breakdown on Lithium Silicide Surfaces

Silicon anodes are a promising material for lithium ion batteries due to their large theoretical capacity for storing lithium. When the battery is charging, the anode works by alloying lithium ions with the silicon anode where the lithium ions are reduced. In addition to the lithium ions being reduced, unwanted side reduction reactions of the electrolyte also occur. When the electrolyte reductively decomposes at the anode surface, a solid-electrolyte interphase (SEI) is formed. Fluoroethylene carbonate (FEC) is added to the electrolyte to make a more robust SEI which prevents further electrolyte decomposition. From FEC reductive decomposition, the primary reduction products are CO2, CH2CHO, and F-. While the decomposition products have been discovered, the lowest energy surface facet which promotes the breakdown of FEC into those products is still unknown. Here FEC and its reduction products are being studied on different lithium silicide surfaces using density functional theory. The lithium silicide phases under consideration are the crystalline LiSi phase with a low lithium concentration and the crystalline Li15Si4 phase with a higher lithium concentration. All unique low index surface facets are considered for each lithium silicide phase. The interactions of FEC and its dissociation products are analyzed on the different anode surface facets to determine the surface sensitivity of FEC breakdown. From the binding energies of the FEC reactant and the CO2, CH2CHO, and F- products on the lithium silicide surface facets, FEC dissociation reaction energies are calculated. The facet on which SEI formation begins to form is determined from the reaction energies for both the low and high concentration lithium silicide anodes. This material is based upon work supported by the U. S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under contract number DE-SC0014664. Use of the Center for Nanoscale Materials, an Office of Science user facility, is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02-06CH11357.

Investigation of lithium distribution in the rat brain ex vivo using lithium-7 magnetic resonance spectroscopy and imaging at 17.2T.

Lithium is the first-line mood stabilizer for the treatment of patients with bipolar disorder. However, its mechanisms of action and transport across the blood-brain barrier remain poorly understood. The contribution of lithium-7 magnetic resonance imaging (7 Li MRI) to investigate brain lithium distribution remains limited because of the modest sensitivity of the lithium nucleus and the expected low brain concentrations in humans and animal models. Therefore, we decided to image lithium distribution in the rat brain ex vivo using a turbo-spin-echo imaging sequence at 17.2T. The estimation of lithium concentrations was performed using a phantom replacement approach accounting for B1 inhomogeneities and differential T1 and T2 weighting. Our MRI-derived lithium concentrations were validated by comparison with inductively coupled plasma-mass spectrometry (ICP-MS) measurements ([Li]MRI =1.18[Li]MS , R=0.95). Overall, a sensitivity of 0.03mmol/L was achieved for a spatial resolution of 16μL. Lithium distribution was uneven throughout the brain (normalized lithium content ranged from 0.4 to 1.4) and was mostly symmetrical, with consistently lower concentrations in the metencephalon (cerebellum and brainstem) and higher concentrations in the cortex. Interestingly, low lithium concentrations were also observed close to the lateral ventricles. The average brain-to-plasma lithium ratio was 0.34±0.04, ranging from 0.29 to 0.39. Brain lithium concentrations were reasonably correlated with plasma lithium concentrations, with Pearson correlation factors ranging from 0.63 to 0.90.

Electrostatic Double Layer Flash Memory Based on Two-Dimensional Crystals

A new type of flash memory will be presented based on the electrostatic doping of two-dimensional crystals using ions. The proposed device consists of two, 2D crystals separated by a 2D electrolyte through which the ions can pass. The top 2D crystal comprises the channel of a field-effect transistor (FET), while bottom 2D crystal is a backgate. When the ions are near the surface of the channel, they induce image charge in the channel and the device is the low resistance, or ON state. When the ions are pulled back to the backgate by an applied field, the device is in the high resistance or OFF state. The 2D electrolyte is cobalt crown ether phthalocyanine (CoCrPc) plus a salt, which can be deposited on the surface of 2D crystals simply by drop casting and annealing. The crown ethers solvate metal ions, and the ions can pass through the cavity of the crowns. Density functional theory (DFT) calculations show that the crown ethers present a small barrier to ion transport required for fast (nanosecond) switching, but the height of the barrier will be increased for long retention both by the image charge induced in the channel and by modulating the gate bias. The current-voltage characteristics of a simplified device architecture (monolayer CoCrPc:LiClO4 on graphene) will be presented. The graphene FET can be reconfigureably programmed by the 2D electrolyte, achieving sheet carrier densities of 4 x 1012 cm-2 at a low lithium concentration of 5 crown ethers to 1 Li+. Based on the geometric packing of the molecules, as determined by scanning tunneling microscopy, the doping density is predicted to increase to 5 x 1013 cm-2 at a crown ether to lithium ratio of 1:1. State retention measurements show that the two states can be retained for at least 30 minutes (maximum time measured to date) with a memory window of 10 uA. To increase the ON/OFF ratio and therefore the memory window, MoS2 FETs doped with the 2D electrolyte were also fabricated and similar bistable behavior is observed. This work was supported in part by the Center for Low Energy Systems Technology (LEAST), one of six SRC STARnet Centers, sponsored by MARCO and DARPA, and NSF grant #ECCS-GOALI-1408425. Figure 1

Measuring Oxygen Release from Delithiated LiNixMnyCo1-x-yO2 and Its Effects on the Performance of High Voltage Li-Ion Cells

There can be a trade-off between the lifetime and energy density of LiNixMnyCo1-x-yO2 (NMC)-containing cells that depends on their upper cutoff voltage. This work applies thermogravimetric analysis coupled with mass spectrometry (TGA-MS) to measure the release of oxygen from delithiated NMC electrode materials at high electrode potentials, i.e., low lithium content. This release is observed at relatively mild temperatures as low as 40°C. The amount of oxygen released is greatly limited using single crystal NMC particles. Electrochemical measurements demonstrate a correlation between TGA-MS results and the cycling performance of NMC/graphite cells. X-ray photoelectron spectroscopy complements the TGA-MS results and provides evidence of the solid electrolyte interphase decomposition. The results in this work offer strong support that the release of oxygen from NMC can cause oxidative decomposition of the electrolyte and is a major reason why high voltage cells can generate gas and can have poor capacity retention.

Hysteretic Phenomena Between Charging and Discharging Process in LiNi0.5Mn1.5O4

Introduction LiNi0.5Mn1.5 O4-σ (LNMO) cathode material for lithium ion batteries are promising because of the high-energy density of 686 Wh/kg. However, the large hysteresis between the charging and the discharging profiles induces the low energy efficiency. Andrej et. al. found a hysteresis in the phase transition of LiNi0.5Mn1.5 O4 during battery operation in a range; the solid solution and two phase coexisting reaction for low lithium concentration dominate the charging and discharging, respectively[1]. Meanwhile, the factors determining the extent of the overpotential during the charging/discharging have not been understood. In this study, we measured in-situXAFS and XRD of LNMO and discussed the factors determining the over(under)potential. Experimental Commercial LNMO (Kojundo Chemical Laboratery Co., Ltd. Japan) was used in this study. The cathode was composed of LNMO, carbon black, and polyvinylidenefluoride with a weight ratio of 80:10:10. The cathode and lithium metal anode were separated by a polypropylene membrane separator. LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC) was used as the electrolyte. The 2032-type coin cell with X-Ray windows was assembled in an argon-filled glove box. We first charged the cell to 4.85 V at a rate of 1.0 C and took 10 minutes for rest when the voltage got to 4.85 V. We subsequently discharged the cell at a rate of 1.0 C to 3.5 V. In-situ Ni K-edge XANES measurement was performed in a transmission mode at beamline 5S1 of Aichi Synchrotron Radiation Center. We took 80 sec. measurement with 40 sec. interval per scan and the patterns were analyzed by using “Athena” program[2]. In-situ XRD measurement was also conducted at beamline 5S1 of Aichi Synchrotron Radiation Center. Results and Discussion The charge/discharge curves show two reaction plateaus: ≃ 4.0 V and 4.7 V regions for LNMO as shown in figure 1. Previous studies reported that these plateaus are ascribed to Mn and Ni redox reactions, respectively[1]. The dashed line indicates the estimated OCV from 1/10C charge-discharge cycle performed separately. We found that both the gap between the CCV (closed circuit voltage) and estimated OCV (open circuit voltage) curve and the gradient of CCV during discharging are larger than that during charging. We anticipate that discharging process requires larger overpotential kinetically, since charging process is a lithium-extraction process through the large lattice spacing requiring little lattice change and discharging process is a lithium-insertion process as expanding the lattice spacing. The gradient is extremely steep for low lithium concentration region( 0.3 ≤ x ≤ 0.5) during discharging, suggesting the requirement for a significant overpotential. Interestingly, Ni-K edge XANES peak top energy during charging plotted in Figure 2 shows the same tendency; the change rate is small before x = 0.5 and increases quickly afterwards. The peak top energy during charging changes in the same way. These results suggest that Ni ion plays more as the redox center in the range of x ≤ 0.5 and that a different redox process in addition to Ni oxidation occurs in the range of x ≥ 0.5. Based on previous studies, it is hardly likely that Mn4+ change to Mn5+, and O2p would attend the charge compensation in the latter region. Taking the above discussion into account, we consider that, during discharging in the range of 0.3 ≤ x ≤ 0.5, a considerable large lattice expansion is required for both lithium-insertion and valence state change from Ni3+ to Ni2+; the ionic radius of Ni3+ and Ni2+ is 0.57 and 0.69 Å, respectively. Further, we deduce that the kinetically preferred state for facilitating the abrupt change requires the significant overpotential. Our in-situ XRD results confirmed the above discussion from the viewpoint of the difference in the crystal structure between charging and discharging. We plan to talk about the details of the crystal structure and Mn-Kedge XAFS result for detailed discussion at PRiME 2016. Conclusion We measured in-situ XAFS and XRD of LNMO and consider that the over(under)potential strongly depends on the kinetic reaction mode, i.e.charging and discharging, and the charge compensator.

Lithium Permeation through Thin Lithium–Silicon Films for Battery Applications Investigated by Neutron Reflectometry

AbstractIn the ongoing search for new negative electrode materials for lithium‐ion batteries, amorphous silicon with a theoretical specific capacity of almost 4000 mA h g−1 is still one of the most promising candidates. In order to optimize cycling behavior, prelithiation of silicon is discussed as possible solution. Yet, little is known about kinetics in the Li‐Si system, especially with a low lithium content. Using neutron reflectometry as a tool, lithium permeation through amorphous LixSi layers was probed during annealing. From the results a lithium permeability (diffusivity×solubility) of P=(3.3±0.9)×10−21 m2 s−1 is derived for LixSi (x≈0.1), which is identical to that of pure amorphous silicon.

Lithium attenuated the behavioral despair induced by acute neurogenic stress through blockade of opioid receptors in mice

Major depressive disorder is disease with high rate of morbidity and mortality. Stressful events lead to depression and they can be used as a model of depression in rodents. In this study we aimed to investigate whether lithium modifies the stressed-induced depression through blockade of opioid receptors in mice. We used foot shock stress as stressor and forced swimming test (FST), tail suspension test (TST) and open field test (OFT) to evaluation the behavioral responses in mice. We also used naltrexone hydrochloride (as opioid receptor antagonist), and morphine (as opioid receptor agonist). Our results displayed that foot-shock stress significantly increased the immobility time in TST and FST but it could not change the locomotor behavior in OFT. When we combined the low concentrations of lithium and naltrexone a significant reduction in immobility time was seen in the FST and TST in comparison with control foot-shock stressed group administered saline only. Despite the fact that our data showed low concentrations of lithium, when administered independently did not significantly affect the immobility time. Also our data indicated that concurrent administration of lithium and naltrexone had no effect on open field test. Further we demonstrated that simultaneous administration of morphine and lithium reverses the antidepressant like effect of active doses of lithium. Our data acclaimed that we lithium can augment stressed-induced depression and opioid pathways are involved in this action.

Electrode Based on Oxyphosphates as Anode Materials for High Energy Density Lithium-ion Batteries

Lithium-ion batteries (Li-ion) are interesting devices for electrochemical energy storage for most emerging green technologies such as wind and solar technologies or hybrid and plug-in electric vehicles or for classical electrical devices such as laptops, phones or other electronic tools. Nevertheless, the oxygen release at high potentials in the present commercialized electrode materials (e.g. LiCoO2) leads to high thermal instability of these oxides and thus to many safety problems. This safety problem is more pronounced for stationary applications for which large size batteries were needed. Polyanionic materials in general, and particularly phosphates were well renowned by their high structural stability which are essential to overcome the above mentioned safety issue. Here, we present the structural and the electrochemical performances of three oxyphosphates M0.5TiOPO4 (M: Ni, Co, Fe). More than 300 mAh/g discharge capacity could be delivered by these phosphates under relatively high cycling rate. The lithium insertion/extraction mechanism is composed from an intercalation process for low lithium content to a conversion mechanism for higher lithium concentration leading to the extrusion of the transition metal M from the structure.

Ab initiostudy of anisotropic mechanical properties of LiCoO2 during lithium intercalation and deintercalation process

The mechanical properties of LixCoO2 under various Li concentrations and associated anisotropy have been systematically studied using the first principles method. During the lithium intercalation process, the Young's modulus, bulk modulus, shear modulus, and ultimate strength increase with increasing lithium concentration. Strong anisotropy of mechanical properties between a-axis and c-axis in LixCoO2 is identified at low lithium concentrations, and the anisotropy decreases with increasing lithium concentration. The observed lithium concentration dependence and anisotropy are explained by analyzing the charge transfer using Bader charge analysis, bond order analysis, and bond strength by investigating partial density of states and charge density difference. With the decrease of Li concentration, the charge depletion in the bonding regions increases, indicating a weaker Co-O bond strength. Additionally, the Young's modulus, bulk modulus, shear modulus, and toughness are obtained by simulating ab initio tensile tests. From the simulated stress-strain curves, LixCoO2 shows the highest toughness, which is in contraction with Pugh criterion prediction based on elastic properties only.

Lithium in the Kidney: Friend and Foe?

Trace amounts of lithium are essential for our physical and mental health, and administration of lithium has improved the quality of life of millions of patients with bipolar disorder for >60 years. However, in a substantial number of patients with bipolar disorder, long-term lithium therapy comes at the cost of severe renal side effects, including nephrogenic diabetes insipidus and rarely, ESRD. Although the mechanisms underlying the lithium-induced renal pathologies are becoming clearer, several recent animal studies revealed that short-term administration of lower amounts of lithium prevents different forms of experimental AKI. In this review, we discuss the knowledge of the pathologic and therapeutic effects of lithium in the kidney. Furthermore, we discuss the underlying mechanisms of these seemingly paradoxical effects of lithium, in which fine-tuned regulation of glycogen synthase kinase type 3, a prime target for lithium, seems to be key. The new discoveries regarding the protective effect of lithium against AKI in rodents call for follow-up studies in humans and suggest that long-term therapy with low lithium concentrations could be beneficial in CKD.

Electrochemical lithiation/delithiation kinetics and capacity of phosphate tungsten bronze and its chemically pre-lithiated derivatives in aqueous solutions

Monophosphate bronze (PW8O26, WPB) was synthesized by low-temperature (650 °C) heating of 12-tungstophosphoric acid (WPA). Its lithiated derivative with a low lithium content (Li3-WPB) was synthesized by heating lithium salt of WPA at 650 °C. Its lithiated derivative with a high lithium content was synthesized by mechanochemical lithiation of Li3WPB (Lin-WPB) (n > 3), followed by heat treatment at 650 °C. X-ray powder diffraction analysis confirmed that the bronze structure changed with the increase of the incorporated lithium content. These bronzes were investigated from the aspect of lithiation/delithiation kinetics in an aqueous saturated LiNO3 electrolyte solution. By cyclic voltammetry, both the kinetics of intercalation/deintercalation and the coulombic capacity were found to decrease with the increase of initial lithium content, in agreement with literature data for electrochemically lithiated tungstophosphate bronzes. Monoclinic lithium-free bronze PW8O26, as the most promising material, was subjected to a further detailed galvanostatic investigation coupled with the LiFe0.95V0.05PO4/C composite as a cathode material in an aqueous battery. In comparison to its behavior in an organic electrolyte, a considerably lower initial capacity of the bronze electrode was measured. However, its cyclic stability was much better in an aqueous than in an organic electrolyte.

Brittle versus ductile fracture mechanism transition in amorphous lithiated silicon: From intrinsic nanoscale cavitation to shear banding

Large-scale atomistic simulations were performed to investigate the fracture behaviors of amorphous lithiated silicon. The simulation results revealed that as the lithium concentration increases, there exists a transition in fracture mechanism from intrinsic nanoscale cavitation to extensive shear banding ahead of the crack tip. It is shown that the observed fracture-mechanism transition can be understood from the changing ratio between critical stresses for cavitation and plastic yield under increasing lithium content. Furthermore, we investigated the mechanistic details of cavitation (i.e. growth of nanovoids) in amorphous lithiated silicon using fully three-dimensional atomistic simulations. It was revealed that in a low lithium concentration environment, an initial void grows heterogeneously by merging with neighboring nucleated voids. However, at high lithium concentrations, the initial void continues to grow in a homogeneous mode. These atomistic mechanisms provide a fundamental understanding of how silicon anodes in lithium-ion batteries fracture during lithiation.

Lithium migration at low concentration in TiO2 polymorphs

We report an atomistic simulation study at low concentration of lithium in scanning all the possible pathways for Li migration in TiO2 polymorphs. We are particularly interested in showing the effects of the structural properties on the intercalation energies and on the energy barriers for ion diffusion. The most favourable directions for Li+ transport are highlighted and we observe an anisotropic diffusion in rutile, brookite and TiO2-B whereas the diffusion is isotropic in the case of anatase. The lowest energy barrier is calculated in rutile but it is not a key factor to determine the efficiency of Li-battery materials. Intercalation energies of stable and transition states are however important data to take into account as well as the Li pathway in order to evaluate the potentiality of each polymorph for Li migration.

Therapeutic Drug Monitoring of Lithium: A Study of the Accuracy and Analytical Variation Between Laboratories in Denmark.

Serum lithium is monitored to ensure levels within the narrow therapeutic window. This study examines the interlaboratory variation and inaccuracy of lithium monitoring in Denmark. In 16 samples consisting of (1) control materials (n = 4), (2) pooled patient serum (n = 5), and (3) serum from individual patients (n = 7), lithium was measured in 19 laboratories using 20 different instruments. The lithium concentrations were targeted by a reference laboratory. Ion-selective electrode (n = 5), reflective spectrophotometric (RSM, n = 5), and spectrophotometric (n = 10) methods were used. Acceptable accuracy-interpreted as total differences from target values (bias) less than or equal to ±12%-was generally found in patient samples above 0.7 mmol/L. Below 0.7 mmol/L, 8 instruments had 2 or more patient samples exceeding a difference to the targeted reference value of >12%. Seven of these instruments had a systematic positive or negative bias and more so at lower lithium concentrations. Three poorly calibrated instruments were found in the ion-selective electrode group, 3 in the spectrophotometric group, and 2 in the RSM group. The instruments using reflectance spectrophotometry (RSM) were on average 21% positively biased when measuring control materials. However, this effect was not observed in patient samples. Large interlaboratory variation was found below 0.7 mmol/L because of 7 instruments with a poor accuracy and 1 with poor precision. Methods should be recalibrated or substituted. Controls below 0.7 mmol/L are recommended.

Examining the Electrochemical Impedance at Low States of Charge in Lithium- and Manganese-Rich Layered Transition-Metal Oxide Electrodes

Lithium- and manganese-rich layered transition-metal oxide (LMR-NMC) intercalation electrodes are projected to enable batteries with high energy density and low costs for energy. However, implementation of LMR-NMC materials are challenged by life limiting mechanisms as well as less than desired rate performance. Here-in, we use electrochemical characterization of LMR-NMC electrodes to examine the large magnitude of impedance and the asymmetric polarization between charge and discharge at low states of charge (SOC). The lithium metal oxide cathode materials examined were LMR-NMC and standard NMC both from Toda Kogyo (Japan). The LMR-NMC material, referred to as HE5050, had the composition 0.5Li2MnO3•0.5LiMn0.375Ni0.375Co0.25O2 (or in layered notation Li1.2Ni0.15Mn0.55Co0.10O2). The NMC material had composition of Li1+x(Ni1/3Mn1/3Co1/3)1-xO2 and can be considered to be the commercial standard stoichiometry for Li-ion transportation cells at the time of this publication. Full cells used A12 graphite (Conoco Phillips) and half cells used lithium metal (FMC Lithium) both with standard LiPF6based carbonate electrolyte. A three electrode pouch cell was utilized for the asymmetry polarization experiments in the study, with a composite LMR-NMC electrode as the working electrode, lithium metal was used as the reference and counter electrodes The area-specific impedance (ASI) of LMR-NMC in Fig. 1 displays a similar dependency as standard layered lithium metal oxides when compared as a function of voltage rather than SOC. The increasing and asymmetric behavior of the polarization in LMR-NMC measured at low SOC is hypothesized to be the result of the differing lithium contents and lithium mobilities in the heterogeneous, nano-composite metal oxide material. Transport of lithium within LMR-NMC is suggested to be governed by the relatively facile nickel- and cobalt-rich domains even as this domain appears to reach full lithiation. As the majority of capacity at low SOC in LMR-NMC is associated with the lithium- and manganese-rich domains, the observed high impedance presents a significant hurdle to utilizing this capacity in moderate power-to-energy ratio applications. Much work is needed to clarify the transport and structural mechanism in LMR-NMC. Other studies have shown the structural transformation known as voltage fade is less severe with lower lithium content. However, lowering the lithium stoichiometry also tends to lower the specific energy of the material at beginning of life. Optimizing the stoichiometry of the lithium and manganese to achieve a maximum specific energy over life at relevant discharge rates is a potentially viable path forward. Figure 1

Electrochemical Stiffness Measurements of Graphite Anodes for Li-Ion Batterie

We report on measurement of the electrochemical stiffness of the graphite anodes during Li exchange in Li-ion batteries. Graphite is the most common anode material used in commercial Li-ion batteries. During lithiation and delithiation of the graphite anodes, Li-graphite intercalation compounds with varying Li content (Li x C6, 0 ≤ x ≤ 1), and graphene layer spacing are formed. Hence, Li intercalation and de-intercalation causes considerable mechanical changes in the whole electrode. We use curvature bending measurements to monitor stress changes in a thin graphite electrode constrained on an inert, rigid substrate. In a separate experiment, we employ digital image correlation to track strain changes in a free-standing, unconstrained graphite electrode. Combining in-situstress and strain analyses enables us to extract the potential-dependent stiffness of the graphite anodes during lithiation-delithiation cycles. As expected, graphite anodes develop compressive stress during lithiation (ca. 10 MPa). The compressive stress is removed during delithiation. Strain response also corresponds with the Li deposition and removal, as graphite anodes expand during lithiation (ca. 1.5 % linear strain) and contract over delithiation. The electrode exhibits an initially stiff response at high potentials and low lithium contents, and then gradually softens during early formation of dilute stage I of the Li-graphite intercalation compound. As the potential is lowered and lithium content increases, several oscillations in the stiffness are observed, which correspond with the phase transitions during different stages of graphite lithiation. The evolution of stress, strain and stiffness data provides quantitative information on the coupled electro-chemo-mechanical response of the battery electrodes and insight on material strategies to increase battery reliability.

Analysis of the Aqueous/Solid Interface in a Mixed Aprotic/Aqueous Lithium-Air Battery

A rechargeable Li-air cell is promising due to its high theoretical energy density of about 11140 Wh/kg. A practical energy density of approximately 1000 Wh/kg [1] would be still about five times higher compared to a state-of-the-art Li-ion cell. However, there are manifold problems concerning cell chemistry, reaction kinetics and cycleability of Li-air cells. In this study, a mixed aprotic/aqueous Li-air cell with a Li3xLa2/3-xTiO3 (LLTO) solid electrolyte was characterized in a new interface-cell setup. This setup is capable to analyse the polarization contribution caused by the liquid/solid interface between the solid electrolyte and different liquid electrolytes. The cell design is inspired by Abe et al. [2], consisting of two compartments, which are in contact with the solid electrolyte. Four-point electrochemical impedance measurements are performed using two electrodes on both sides. The excitation signal is applied on the outer working electrodes (WE, CE) and the voltage is measured between the inner reference electrodes (RE1, RE2). The impedance spectra are further processed by calculating their distribution of relaxation times, to clearly separate the different processes [3]. The special cell design allows a selective investigation of a single liquid/solid interface process by assembling different symmetric cells, using the same liquid electrolyte in each compartment. By changing the ratio of conducting salt to solvent (Fig. 1), we clearly defined the interface process in a frequency range from 102 Hz to 103 Hz and determined an activation energy of 0,44 eV. Furthermore, the interface process is a major contribution to the overall polarization, which even exceeds the contribution of bulk electrolyte and grain boundary for low lithium concentration and low pH-value.

Effect of fluorine and nitrogen on the chemical durability of lithium phosphate glasses

The dissolution of glasses belonging to the systems of composition xLi2O·(100−x)P2O5 (x=38–55mol%) and (55−x/2)Li2O·xLiF·(45−x/2)P2O5 (x=10–30mol%), with and without nitrogen, has been studied through immersion of the samples in water at 95°C using a Soxhlet extractor. In this work, a wide range of compositions prepared by melting has allowed a detailed study of the effect of nitrogen and fluorine in the chemical properties of glasses with variable lithium contents. In lithium phosphorus oxynitride glasses, it was demonstrated that low lithium and high nitrogen contents improve the chemical durability. However, there is a maximum of nitrogen percentage from which the durability is not further improved. In lithium phosphorus fluoro-oxynitride glasses, fluorine introduction leads to a deterioration of the phosphate glasses; however, the introduction of nitrogen in these glasses increases significantly the chemical durability. The structural changes obtained by NMR and XPS are used to explain the effect of lithium, fluorine and nitrogen on the chemical properties. In general, the decrease of non-bridging oxygens and the increase percentage of phosphorus groups with nitrogen increase the chemical resistance.