Lithium Flux Research Articles

Cosmic-Ray Lithium Production at the Nova Eruptions Followed by a Type Ia Supernova.

Recent measurements of cosmic-ray (CR) light nuclei by AMS-02 have shown that there is an unexpected component of CR lithium whose spectral index is harder than that expected from the secondary production scenario. We propose the nearby type Ia supernova following a nova eruption as the origin of lithium nuclei in the CRs. By fitting the data of CR protons, helium, and lithium fluxes provided by AMS-02 with our theoretical model we show that this scenario is consistent with the observations. The observational tests that can check our hypothesis are briefly discussed.

Mechanical Failure Analysis of Graphite Anode Particles with PVDF Binders in Li-Ion Batteries

The mechanical failure of electrodes is one of the main mechanisms of degradation in Li-ion batteries. Many studies have been carried out on the fracture inside a single particle; however, studies on particles with binders are limited. In this study, we investigated stress development under the anisotropic lithium flux in a graphite particle partially attached to an ionically non-conductive polyvinylidene difluoride (PVDF) binder. The study reveals that the location of the maximum stress depends on the particle sizes and C-rates due to the anisotropic lithium intercalation and the mechanical failure can initiate with high probability either at the particle center or at the binder interface according to different sizes and C-rates. The simulations showed that small particles under low charging rates tend to produce high stress at the edge of the particle/binder interface, while large particles under high charging rates tend to generate high stress inside the particle. The possible fracture locations are determined by competition of the interface fracture due to expansion and at the inner fracture due to the gradients of lithium concentration. We also studied the effect of binder geometries on the level of stress and found that the stress concentration near the binder edges increases the possibility of the binder debonding as the binder size increases and the angle between the binder and particle decreases. The study will expand to crack propagation in the cluster of particles, eventually linking to the capacity fade issue due to mechanical failures.

The Inverse Perovskite Nitrides (Sr3N2/3–x)Sn, (Sr3N2/3–x)Pb, and (Sr3N)Sb: Flux Crystal Growth, Crystal Structures, and Physical Properties

Black single crystals with metallic luster of (Sr3N2/3–x)E (E = Sn, Pb) and (Sr3N)Sb were grown in lithium flux from strontium nitride, Sr2N, and tin, lead, or antimony, respectively. Nitrogen deficiency in the tin and the lead compound is a result of the higher ionic charge of the tetrelide ions E4– as compared to the antimonide ion Sb3–. In contrast to microcrystalline samples from solid state sinter reactions obtained earlier, the flux synthesis induces nitrogen order in the nitrogen deficient tetrelides. The antimony compound crystallizes as inverse cubic perovskite [a = 517.22(5) pm, Z = 1, space group Pm3m, no. 221] with fully occupied nitrogen site, whereas the nitrogen deficient tin and lead compounds exhibit partially ordered arrangements and a certain phase width in respect to nitrogen contents. For the tetrelides, the nitrogen order leads to a cubic 2 × 2 × 2 superstructure [E = Sn: a = 1045.64(8) pm for x = 0, a = 1047.08(7) pm for x = 0.08; and E = Pb: a = 1050.7(1) pm for x = 0, space group Fm3m, no. 225] as derived from single‐crystal X‐ray diffraction data. The metallic tetrelides show diamagnetic behavior, which is consistent with electronic structure calculations.

Theoretical prediction of fracture conditions for delithiation in silicon anode of lithium ion battery

Structural instability such as fractures of a silicon anode in a lithium ion battery, intrinsically induced by the large variation of the ratio, Li/Si, upon lithiation and delithiation, limits its potential for commercial use. Here, we study mechanical properties during delithiation in lithiated silicon particles to identify the conditions under which fracture is preventing during delithiation in terms of Li contents and silicon particle sizes. We employed the first principles calculation within the density functional framework combined with the continuum based calculation for the macroscopic mechanical properties. The theoretical limit for the largest crystalline silicon particle size that can prevent fractures upon complete delithiation is ∼0.6 μm at the lithium flux per unit surface area of 5.657 × 10−2 s−1 nm out of amorphous Li3.75Si, much larger than the critical fracture size (0.15 μm) that occurs during the first lithiation of crystalline Si. Furthermore, fractures during delithiation are nearly unaffected by the silicon particle size for a residual lithium fraction larger than x ∼ 2.1 in amorphous LixSi.

Lithium Dendrite Suppression By Polyethylene Oxide Film Coating on Copper Electrode Enable Lithium Metal Anode

Efforts to realize lithium metal as anode limited by dendrite formation and low Coulombic efficiency. These challenges stem from extensive reaction of lithium with electrolyte, deposition of more dead lithium and formation of unstable solid electrolyte interface. Herein, we revealed a homogeneous lithium deposition and dendrite suppression via regulating lithium flux with polyethylene oxide (PEO) film coated copper electrode in 1M LiTFSI, DME/DOL (v/v 1/1) and 2 wt% LiNO3 electrolyte. PEO coating reinforces a thin and robust SEI layer film formation by hosting lithium and regulating the inevitable reaction of lithium with electrolyte. The modified electrode showed a stable and an extremely excellent Coulombic efficiency over 200 cycles with low voltage hysteresis (~30 mV) at rate of 1 C. In comparison the modified electrode tested with 1M LiPF6, EC/DEC (v/v 1/1) electrolyte and showed a rapid capacity fading due to PEO film damage with fluoride ion interaction. This enhanced cycle life and capacity retention results from the synergy of PEO coating, high electrode-electrolyte interface compatibility, stable polar oligomer formation from reduction of 1, 3-dioxolane and generation of SEI stabilizing nitrite and nitride upon lithium nitrate reduction in an ether electrolyte.

On the spectrum of stable secondary nuclei in cosmic rays

The ratio of the fluxes of secondary and primary nuclei in cosmic rays has long been used as an indicator of the grammage traversed in the journey of cosmic ray particles throughout the Galaxy. The basic idea is that primary particles are accelerated in astrophysical sources, such as supernova remnant shocks and eventually propagate in the Galactic volume, occasionally interacting with gas, mainly in the disc of the Galaxy, and there they produce secondary nuclei through spallation. At sufficiently high energy, typically $\gtrsim 100$ GeV/n, the ratio of fluxes of the secondary nucleus to that of the main primary nucleus is found to scale as $E_{k}^{-\delta}$, where $E_{k}$ is the energy per nucleon (a conserved quantity in spallation reactions) and $\delta$ identifies the energy dependence of the diffusion coefficient. The same shock waves that may be responsible for cosmic ray acceleration in the first place also pick up any other charged particle in the upstream, provided being above threshold for injection. The secondary nuclei produced by spallation in the interstellar medium are no exception, hence they also get accelerated. This effect is unavoidable, only its strength may be subject of debate. We compute the spectrum of secondary elements such as boron and lithium taking into account shock reacceleration and compare our predictions with the recent observations of the B/C ratio and preliminary measurements of the boron and lithium flux. Both these sets of data seem to confirm that reacceleration of secondary nuclei indeed plays an important role, thereby affecting the validity of those scaling rules that are often used in cosmic ray physics.

Spectroscopic measurements for deuterium retention and lithium influx studies with lithium limiter on FTU

Spectroscopic measurements to determine deuterium and lithium fluxes were performed in recent experiments on FTU with a liquid lithium limiter (LLL) and an actively cooled limiter (CLL) using a multichannel spectrometer and using LiI–Dα filtered photodiodes. Using the S/XB method in combination with an absolute calibration, measurements of the LiI (670.8nm) and Dβ (464.8nm) spectral lines were used to estimate the deuterium and lithium fluxes from the limiters. The estimation of the lithium fluxes has shown increased values when the CLL is closer towards the last closed magnetic surface (LCMS), according to the measurements of infrared camera. This work shows that the spectroscopic diagnostics in the visible range can be an efficient tool to determine deuterium and liquid metal fluxes in FTU in order to better investigate the interaction between the plasma and the limiter materials.

Reviving Lithium-Metal Anodes for Next-Generation High-Energy Batteries.

Lithium-metal batteries (LMBs), as one of the most promising next-generation high-energy-density storage devices, are able to meet the rigid demands of new industries. However, the direct utilization of metallic lithium can induce harsh safety issues, inferior rate and cycle performance, or anode pulverization inside the cells. These drawbacks severely hinder the commercialization of LMBs. Here, an up-to-date review of the behavior of lithium ions upon deposition/dissolution, and the failure mechanisms of lithium-metal anodes is presented. It has been shown that the primary causes consist of the growth of lithium dendrites due to large polarization and a strong electric field at the vicinity of the anode, the hyperactivity of metallic lithium, and hostless infinite volume changes upon cycling. The recent advances in liquid organic electrolyte (LOE) systems through modulating the local current density, anion depletion, lithium flux, the anode-electrolyte interface, or the mechanical strength of the interlayers are highlighted. Concrete strategies including tailoring the anode structures, optimizing the electrolytes, building artificial anode-electrolyte interfaces, and functionalizing the protective interlayers are summarized in detail. Furthermore, the challenges remaining in LOE systems are outlined, and the future perspectives of introducing solid-state electrolytes to radically address safety issues are presented.

Molecular Beam Epitaxy of lithium niobium oxide multifunctional materials

The role of stoichiometry and growth temperature in the preferential nucleation of material phases in the Li-Nb-O family are explored yielding an empirical growth phase diagram. It is shown that while single parameter variation often produces multi-phase films, combining substrate temperature control with the previously published lithium flux limited growth allows the repeatable growth of high quality single crystalline films of many different oxide phases. Higher temperatures (800–1050°C) than normally used in MBE were necessary to achieve high quality materials. At these temperatures the desorption of surface species is shown to play an important role in film composition. Using this method single phase films of NbO, NbO2, LiNbO2, Li3NbO4, LiNbO3, and LiNb3O8 have been achieved in the same growth system, all on c-plane sapphire. Finally, the future of these films in functional oxide heterostructures is briefly discussed.

In Situ Observation and Mathematical Modeling of Lithium Distribution within Graphite

Lithium forms ordered stages when it reacts with graphite. These stages have distinct colors; therefore, optical microscopy gives direct information about the lithium concentration in the graphite. Here we present in situ optical images during charging and discharging of a graphite electrode. Stages are observed to coexist with each other even after extended rest. There is considerable spatial nonuniformity on the microscale. To predict this concentration distribution, we employ a model which combines porous-electrode theory and Cahn-Hilliard phase-field theory to describe the flux of lithium within the graphite. The model closely matches the experimental voltage and concentration distribution. The spatial nonuniformity can be approximated with a relatively simple model of distributed resistances. Finally, we discuss the implications of using the phase-field model instead of a solid-solution model for prediction of lithium plating. The two models give similar predictions of cell voltage and risk of lithium plating under many operating conditions, with the main difference being the relaxation of concentration gradients within particles during rest. The distributed-resistance model shows a higher risk of lithium plating because well-connected particles are overworked as their more-resistive neighbors require a higher driving force for passage of current.

Single Crystal Growth and Anisotropic Magnetic Properties of Li2Sr[Li1 − xFexN

Up to now, investigation of physical properties of ternary and higher nitridometalates has been severely hampered by challenges concerning phase purity and crystal size. Employing a modified lithium flux technique, we are now able to prepare sufficiently large single crystals of the highly air and moisture sensitive nitridoferrate Li 2 Sr[Li 1 − x Fe x N] 2 for anisotropic magnetization measurements. The magnetic properties are most remarkable: large anisotropy and coercivity fields of 7 Tesla at T = 2 K indicate a significant orbital contribution to the magnetic moment of iron. Altogether, the novel growth method opens a route towards interesting phases in the comparatively recent research field of nitridometalates and should be applicable to various other materials.

Soft-contact conductive carbon enabling depolarization of LiFePO4 cathodes to enhance both capacity and rate performances of lithium ion batteries

Conductive nanocarbons generally are used as the electronic conductive additives to contact with active materials to generate conductive network for electrodes of commercial Li-ion batteries (LIBs). A typical of LiFePO4 (LFP), which has been widely used as cathode material for LIBs with low electronic conductivity, needs higher quantity of conductive nanocarbons to enhance the performance for cathode electrodes. In this work, we systematically studied three types of conductive nanocarbons and related performances in the LFP electrodes, and classify them as hard/soft-contact conductive carbon (named as H/SCC), respectively, according to their crystallite size, surface graphite-defect, specific surface area and porous structure, in which SCC can generate much larger contact area with active nano-particles of cathode materials than that of HCC. It is found that LFP nanocrystals wrapped in SCC networks perform significantly enhanced both capacity and rate performance than that in HCC. Combined experiments with multiphysics simulation, the mechanism is that LFP nanoparticles embedded in SCC with large contact area enable to generate higher depolarized effects with a relatively uniform current density vector (is) and lithium flux vector (NLi) than that in HCC. This discovery will guide us to how to design LIBs by selective using conductive carbon for high-performance LIBs.

Conceptual design of a pre-loaded liquid lithium divertor target for NSTX-U

In this work, a conceptual design for a pre-filled liquid lithium divertor target for the National Spherical Torus Experiment Upgrade (NSTX-U) is presented. The design is aimed at facilitating experiments with high lithium flux from the plasma facing components (PFCs) in NSTX-U and investigating the potential of capillary based liquid lithium components. In the design, lithium is supplied from a reservoir in the PFC to the plasma facing surface via capillary action in a wicking structure. This working principle is also demonstrated experimentally. Next, a titanium zirconium molybdenum (TZM) prototype design is presented, required to withstand a steady state heat flux peaking at 10MWm−2 for 5s and edge localized modes depositing (130kJ in 2ms at 10Hz). The main challenge is to sufficiently reduce the thermal stresses. This is achieved by dividing the surface into brushes and filling the slots in between with liquid lithium. The principle of using this liquid “interlayer” allows for thermal expansion and simultaneously heat conduction, and could be used to significantly reduce the demands to solids in future PFCs. Lithium flow to the surface is analyzed using a novel analytical model, ideally suited for design purposes. Thermal stresses in the PFC are analyzed using the finite element method. The requirements are met, and thus a prototype will be manufactured for physical testing.

Solvent stable nanoporous poly (ethylene-co-vinyl alcohol) barrier membranes for liquid-liquid extraction of lithium from a salt lake brine

Loss of organic extraction in membrane extraction process could be avoided by using an ion permeable, solvent stable barrier membrane. Development of solvent stable materials has been a key issue for liquid-liquid membrane extraction. A new type of solvent resistant membrane, prepared from block copolymer poly (ethylene-co-vinyl alcohol) (EVAL) via immersion precipitation, is introduced as the barrier in membrane extraction of lithium from a real salt lake brine. The influence of EVAL concentration on the casting solution viscosity and the membrane properties was investigated. The membranes were characterized by scanning electron microscopy (SEM), water uptake, pure water flux, mechanical strength, and Li+ diffusion flux. Membrane phase separation was conducted at a temperature below the crystallization temperature of the polymer to ensure suitable membrane structure. The membrane prepared from 30wt% EVAL content showed a Li+ flux of 2.7×10−8molcm−2s−1 at a Li+ feed concentration of 0.1mol/L in a diffusion test. Using a tributylphosphate (TBP)/kerosene extractant, the lithium flux in a membrane extraction showed a linear relationship with the feed lithium concentration. In addition, long term stability tests showed a stable lithium extraction flux for about 1037h. These results indicate that EVAL material is a promising stabilizing barrier membrane in liquid-liquid extraction of lithium.

Spectroscopic measurements of lithium influx from an actively water-cooled liquid lithium limiter on FTU

Since 2006, experiments using a liquid lithium limiter (LLL) were successfully performed on FTU, pointing out the problem of the quantity of lithium in the plasma, especially in conditions of strong evaporation due to the high temperature of limiter surface. In order to avoid the strong evaporation it is necessary to control the temperature by removing the heat from the limiter during the plasma exposure. To explore this issue a new actively cooled lithium limiter (CLL) has been installed and tested in FTU.Suitable monitors to detect the presence of lithium in the plasma are the spectroscopic diagnostics in the visible range that permit to measure the flux of lithium, coming from the limiter surface, through the brightness of the LiI spectral lines.For this aim an Optical Multichannel Analyser (OMA) spectrometer and a single wavelength impurities monitor have been used.The analysis of the Li influx signals has permitted to monitor the effects of interaction between the plasma and the limiter connected to the thermal load. Particular attention has been paid on the possible occurrence of sudden rise of the signals, which is an index of a strong interaction that could lead to a disruption.On the other hand, the appearance of significant signals gives useful indication if the interaction with the plasma has taken place.

Soft Conductive Carbon Enables Depolarization of LiFePO4 Cathodes to Enhance Both Capacity and Rate Performances of Lithium Ion Batteries

Conductive nanocarbons generally are used as the electronic conductive additives to contact with active materials to generate conductive network for electrodes of commercial Li-ion batteries (LIBs). In this work, conductive nanocarbons are systematically studied and classified as “hard” and “soft” conductive-carbons (named as HCC and SCC), respectively for the first time according to their structures and morphologies. SCC can create larger contact area with active particles of electrodes because it has more percentage of graphite-like (sp2) structures, smaller crystallite size and larger specific surface area than that of HCC. LiFePO4 (LFP)，which has been widely used as cathode materials for EV LIBs with low electronic conductivity, need to contact with conductive network closely to depolarize for cathode electrodes. It is found that LiFePO4 nano-crystals with large contact area wrapped in SCC networks perform significantly enhanced both capacity and charge-discharge rate capacity than that in HCC for the cathode of LIBs. Combined experiments with multiphysics simulation, the mechanism is investigated that LFP nanoparticles embedded with large contact areas enable to generate depolarization networks and enhance the electrochemical performance with a relatively uniform current density vector () and lithium flux vector (). This discovery will guide us to design LIBs with the high energy and power densities for electric vehicles (EVs) applications.

Effect of local velocity on diffusion-induced stress in large-deformation electrodes of lithium-ion batteries

In this work, the contribution of local velocity to the resultant flux of lithium in lithium-ion battery is introduced into the diffusion equation to describe the migration of lithium in the active material of electrodes. The effect of the local velocity on the stress evolution in a spherical electrode made of silicon is analyzed, using the derived diffusion equation and nonlinear theory of elasticity. Two boundary conditions at the surface of the electrode, which represent two extreme conditions of real electrode materials, are used in the stress analysis: one is stress-free, and the other is immobile. The numerical results with the stress-free boundary condition suggest that the effect of the local velocity on the distribution of radial stress and hoop stress increases with the increase of time and the effect of the local velocity on the distribution of lithium is relatively small. In comparison with the results without the effect of the local velocity, the effect of the local velocity is negligible for the immobile boundary condition. The numerical result shows that the use of the immobile boundary condition leads to the decrease of von-Mises stress, which likely will retard the mechanical degradation of electrode and improve the electrochemical performance of lithium-ion battery.

In Situ Observation of Epitaxial Li–Si-Nanostructure Formation on Si(111)

The formation kinetics of lithium–silicon phases was studied in a molecular beam epitaxy environment under ultrahigh vacuum (UHV) conditions. A heated Si(111) substrate was exposed to an incoming lithium flux at a gradually decreasing substrate temperature. The onset of the nucleation and the formation of Li–Si phases were simultaneously observed by in situ synchrotron X-ray diffraction (XRD), azimuthal reflection high-energy electron diffraction (ARHEED), and line-of-sight quadrupole mass spectrometry (QMS) of the desorbing Li. First, Li-induced reconstructions formed, followed by the appearance of nanostructures which grow epitaxially with respect to the Si substrate. Both crystal structures, namely Li12Si7 and Li21Si5, which are thermodynamical stable at elevated temperatures were identified. They form with an epitaxial relationship such that [111]Si ∥ [010]Li12Si7 and [112̅]Si ∥ [100]Li12Si7 as well as [111]Si ∥ [111]Li21Si5 and [011̅]Si ∥ [011̅]Li21Si5. Finally, three-dimensional Li structures appeared on the surface. The in situ measurements were supplemented by ex situ atomic force microscopy and scanning electron microscopy showing the real-space information on three-dimensional Li–Si structures. Similarities and differences compared to a Li-ion battery structure containing a Si anode are discussed. A significant mobility of Si and Li to form nm-sized crystal structures is concluded.

Progress in development and application of lithium based components for Tokamak

Experiments with lithium plasma facing components (PFCs) show promising results for the operation of hot plasma facilities and the general improvement of plasma parameters. The design and development of new tokamak plasma facing material (PFM) based on lithium capillary porous systems (CPS) are described in this paper.The recent progress in the development of limiters with different kinds of CPS is relevant for protection of tokamak PFCs from damage under normal operation, ELMs and disruptions. New PFM eliminates the lithium flux into plasma, its pollution and lithium accumulation.Here we present an overview of the design and the experimental tests of the liquid lithium limiters. These limiters are based on CPS with hard matrix from stainless steel mesh, molybdenum and tungsten. Different types of limiter have been taken into account: the horizontal and vertical rail type limiters with passive and active cooling for investigation the possibility to provide the closed lithium circulation in tokamak chamber; the ring CPS-based limiter for investigation of lithium behavior in limiter scrape-off layer (SOL).Here we also present the preliminary results of the application of the cryogenic techniques for lithium removal from the chamber wall after operation in hot plasma.

Single crystal growth from light, volatile and reactive materials using lithium and calcium flux

We present a method for the solution growth of single crystals from reactive Li and Ca melts and its application to the synthesis of several, representative compounds. Among these, single crystalline LiN, Li(Li)N with = {Mn, Fe, Co}, LiCaN, LiC, LiRh and LiIr from Li-rich flux, as well as CaN, CaNi, CaNi, YbNi, YNi and LaNi from Ca-rich flux could be obtained. Special emphasize is given on the growth of nitrides using commercially available LiN and CaN powders as the nitrogen source instead of N gas.