Evolution Of Lithium Research Articles

Investigating the Morphological Evolution of Lithium Plating/Stripping in Concentrated Electrolyte by Operando X-Ray Computed Tomography

Lithium metal is expected to be next-generation anode because of its low redox potential (-3.04 V vs SHE.) and high specific capacity (3860 mAh g-1), which can achieve high energy density by matching with sulfur or oxygen cathode.1 However, Li metal anode is not viable until now due to the uncontrollable morphology and high activity during Li plating/stripping.2 Especially the growth of Li dendrites, the formation of dead Li, and the broken of unstable SEI (solid electrolyte interphase), result in significant safety risk and low coulombic efficiency. Therefore, to obtain the stable Li metal anode, it’s important to investigate the behavior of Li plating/stripping and the properties of SEI.In recent years, concentrated electrolyte has received great attention as an effective means to improve the performance of lithium anode.3 With the development of these electrolytes, new insights into lithium morphology and SEI composition have also emerged. Compared with that in dilute electrolytes, the solvation structures of Li ions in concentrated electrolytes are changed, thus the SEI components are also changed from solvent derived to lithium salt anion derived.4 As a result, the morphology of Li and the performance of lithium metal anode are effectively improved.5 However, how these changes in solvation structure and SEI composition affect lithium morphology during cycling, which is helpful to gain more information about the basic Li behavior, remains unclear.This study endeavors to elucidate the Li plating/stripping behaviors in concentrated electrolyte by operando X-ray computed tomography. The morphological evolution of Li on Cu current collector surface is investigated. In particular, the growth of Li dendrites and the formation of dead Li, as well as the evolution process between them, have received special attention. These results are helpful to understand basic Li plating/stripping behaviors during cycling and provide guidance to lithium metal anode improvement. Acknowledgment This work was financially supported by the JST, GteX Project (Grant Number: JPMJGX23S3).

(Invited) Mechanisms Governing Lithium Metal and Alloy Anodes in Solid-State Batteries

Solid-state batteries offer the promise of improved energy density and safety compared to lithium-ion batteries, but electro-chemo-mechanical evolution and degradation of materials and interfaces can play an outsized role in limiting their performance. Here, I will present my group’s recent work on understanding structural evolution, interfacial dynamics, and chemo-mechanics in solid-state batteries with both lithium metal and alloy-based anodes. Lithium metal batteries are especially beneficial if used in an “anode-free” configuration in which there is no lithium initially present at the anode current collector. Using X-ray tomography, cryo-FIB, and finite-element modeling, we show that lithium metal anode-free solid-state batteries are intrinsically limited by current concentrations at the end of stripping due to localized lithium depletion. This causes accelerated short circuiting compared to lithium-excess cells. Based on these results, the beneficial influence of metal alloy interfacial layers on controlling lithium evolution and mitigating contact loss from localized lithium depletion will be introduced and discussed. In the second part of the talk, the characteristics of dense, foil-based alloy anodes are introduced. Alloy foils such as aluminum and tin are shown to exhibit improved interfacial stability and better long-term cycling in solid-state batteries compared to liquid-cell batteries due to reduced solid-electrolyte interphase formation. A new design for multiphase aluminum foil alloy anodes is introduced, in which microstructural control over the foil is shown to play a key role in significantly improving reversibility in solid-state batteries. This anode design mitigates chemo-mechanical degradation and offers a paradigm that does away with slurry coating, potentially reducing manufacturing costs. The influence of stack pressure on electrode evolution is investigated. Taken together, these findings show the promise of both lithium metal and alloy anodes for solid-state batteries, with divergent reaction mechanisms giving rise to different operating conditions necessary for each class of materials.

Research on aging mechanism and capacity attenuation of automotive lithium-ion batteries

In order to investigate the internal mechanism and the variation law of capacity attenuation of LIBs, a simplified electrochemical model of the LIBs was established using the nickel-cobalt-aluminum LIBs as the research object, and the aging model of solid electrolyte interface SEI growth and lithium evolution was added to simulate the electrochemical behavior of the batteries. The results showed that the porosity of the anode/diaphragm reduced continually at the start of the cycle, while the SEI film grew continuously. The loss of active materials accelerated as the number of cycles increased, while the side reaction of lithium development continued. Finally, the aging mechanism was confirmed by using microscopic morphology. The results show that the negative particles are obviously crushed and contain white deposited substances. The formation of these compounds increases the oxygen content, reduces the carbon content, reduces the porosity of the electrode, increases the overpotential of the electrolyte transport, and becomes the main reason for the attenuation of the battery life. Finally, the positive particles expand and break, which leads to the sudden reduction of the battery capacity. This study determined the evolution process of aging mechanism in the whole life cycle, and provided a theoretical basis for the establishment of mechanism aging model.

Integrated Design of Homogeneous/Heterogeneous Copper Complex Catalysts to Enable Synergistic Effects on Sulfur and Lithium Evolution Reactions.

Fatal polysulfide shuttling, sluggish sulfur redox kinetics and detrimental lithium dendrites have curtailed the real discharge capacity, working lifespan and safety of lithium-sulfur (Li-S) batteries. Organic small molecule promotors as one type of emerging active catalysts can fulfil the management of the electrochemical species evolution behaviors. Herein, an integrated engineering is organized by synthesizing dual chlorine-bridge enabled binuclear copper complex (Cu2(phen)2Cl2) and its derivative generated in electrolyte (Cu-ETL) as the heterogeneous and homogeneous catalyst, respectively. The well-designed Cu-ETL with a optimized concentration of 0.25 wt% as a homogeneous enabler offers highly utilized Cu centers and the sufficient interface contact for guiding the Li2S nucleation/decomposition reactions. The Cu2(phen)2Cl2 loaded on carbon spheres as an interlayer (Cu-INT) can break through the catalytic limitation resulting from the saturated concentration of Cu-ETL and thus offers an extended manipulation effect. Benefiting from the synergistic effect, the Li-S battery shows stable cycling at 3 C upon 500 cycles with a capacity degradation rate as low as 0.029 % per cycle. Of specific note, an actual cell energy density of 372.1 Wh kg-1 is harvested by a 1.2 Ah-level soft-packaged pouch cell, implying a chance for requiring the demand of high-energy batteries.

Integrated Design of Homogeneous/Heterogeneous Copper Complex Catalysts to Enable Synergistic Effects on Sulfur and Lithium Evolution Reactions

AbstractFatal polysulfide shuttling, sluggish sulfur redox kinetics and detrimental lithium dendrites have curtailed the real discharge capacity, working lifespan and safety of lithium−sulfur (Li−S) batteries. Organic small molecule promotors as one type of emerging active catalysts can fulfil the management of the electrochemical species evolution behaviors. Herein, an integrated engineering is organized by synthesizing dual chlorine‐bridge enabled binuclear copper complex (Cu2(phen)2Cl2) and its derivative generated in electrolyte (Cu‐ETL) as the heterogeneous and homogeneous catalyst, respectively. The well‐designed Cu‐ETL with a optimized concentration of 0.25 wt% as a homogeneous enabler offers highly utilized Cu centers and the sufficient interface contact for guiding the Li2S nucleation/decomposition reactions. The Cu2(phen)2Cl2 loaded on carbon spheres as an interlayer (Cu‐INT) can break through the catalytic limitation resulting from the saturated concentration of Cu‐ETL and thus offers an extended manipulation effect. Benefiting from the synergistic effect, the Li−S battery shows stable cycling at 3 C upon 500 cycles with a capacity degradation rate as low as 0.029 % per cycle. Of specific note, an actual cell energy density of 372.1 Wh kg−1 is harvested by a 1.2 Ah‐level soft‐packaged pouch cell, implying a chance for requiring the demand of high‐energy batteries.

Evolution of lithium in the disc of the Galaxy and the role of novae

Context. Lithium plays a crucial role in probing stellar physics, stellar and primordial nucleosynthesis, and the chemical evolution of the Galaxy. Stars are considered to be the main source of Li, yet the identity of its primary stellar producer has long been a matter of debate. Aims. In light of recent theoretical and observational results, we investigate in this study the role of two candidate sources of Li enrichment in the Milky Way, namely asymptotic giant branch (AGB) stars and, in particular, novae. Methods. We utilised a one-zone Galactic chemical evolution (GCE) model to assess the viability of AGB stars and novae as stellar sources of Li. We used recent theoretical Li yields for AGB stars, while for novae we adopted observationally inferred Li yields and recently derived delay time distributions (DTDs). Subsequently, we extended our analysis by using a multi-zone model with radial migration to investigate spatial variations in the evolution of Li across the Milky Way disc and compared the results with observational data for field stars and open clusters. Results. Our analysis shows that AGB stars clearly fail to reproduce the meteoritic Li abundance. In contrast, novae appear as promising candidates within the adopted framework, allowing us to quantify the contribution of each Li source at the Sun’s formation and today. Our multi-zone model reveals the role of the differences in the DTDs of Type Ia supernovae and novae in shaping the evolution of Li in the various galactic zones. Its results are in fair agreement with the observational data for most open clusters, but small discrepancies appear in the outer disc.

The effect of low-temperature starting on the thermal safety of lithium-ion batteries

With the widespread application of lithium-ion batteries (LIBs) in the field of energy equipment, their probability of starting or operating in low-temperature environments is also increasing. However, there is currently a lack of research on the changes in thermal safety of batteries after use in corresponding environments. In this work, the thermal safety performance, degradation mechanisms and evaluation method of LIBs at low-temperature start-up conditions are studied. The results show that starting at low temperature leads to the decrease of cell capacity. Electrochemical characterization and cell disassembly analysis indicate that the loss of active lithium ions is mainly caused by the evolution of lithium and the growth of solid electrolyte interface films. In addition, the low-temperature startup results in the decrease of thermal runaway (TR) onset temperature and the advance of TR time. In order to quantitatively evaluate the safety state of the LIBs, an evaluation model based on Informer algorithm is established. The model extracts the discharge capacity, discharge energy and dV/dQ as aging characteristic parameters, and extracts TR temperature as thermal safety characteristic parameters. The data set is processed by cubic spline interpolation. After training and verification, the accuracy of the model reaches 80 %.

Introducing surface adsorption lithium storage mechanism to enhance safety of graphite

The thermal stability of lithiated graphite plays an important role in the thermal safety of lithium-ion batteries (LIBs). However, a safer graphite anode usually leads to a lower energy density. This article starts from multiple hazardous factors of lithiated graphite when thermal runaway occurs, considering the impact of defects on the electrochemical performance and thermal safety of graphite electrodes. In this study, turbostratic graphite was prepared as the anode for LIBs. The stacking of graphite was altered to form narrow pores and spherical aggregates, and introducing defects. By varying the ball-milling time, the structural changes of different ball-milled graphites were analyzed. The impact mechanism of defect structure on electrode electrochemical performance and safety performance was investigated. The results show that the spherical structure and large specific surface area are beneficial to increase the active sites and delay the self-heating of the battery. The formation of defects and pores increases the adsorption sites, which makes the surface adsorption of Li+ dominant and improves the ion diffusion. In addition, the dominance of surface adsorption and desorption effectively suppresses the problem of graphite flake peeling and intensified thermal runaway caused by graphite phase transition and lithium evolution heat release at high temperature. The thermal safety test was carried out by accelerated calorimeter (ARC), and its thermodynamics and reaction kinetics were quantitatively analyzed. It was proved that the introduction of surface adsorption lithium storage method successfully delayed the thermal runaway of the battery, realizing the balance between high electrochemical performance and high safety.

Effect of Solid Electrolyte Interphase Heterogeneity on the Lithium Deposition Dynamic: A Phase-Field Approach

Lithium dendrites formation is an inherent drawback in the development of all solid-state lithium batteries technology. These issues remain unsolved due to the multiple and competing troubleshooting during lithium plating and stripping. The inhomogeneous mechanical and chemical properties of the Solid Electrolyte Interphase (SEI) [1] lead to uneven current distribution and unsmooth lithium plating and stripping [2,3,4]. A fine understanding of the relationship between the SEI composition and the dynamic of dendrite growth under polarization is not well established. All computational studies are based on homogeneous SEI on the top of the lithium electrode [5, 6]. The local deformation of the SEI under polarization may lead to several mechanical defect such as cracking and therefore a dendrite nucleation. To link the crack dynamic to the current density, we developed a novel multiphase-field approach in order to probe the first instants of the dendrite formation. Indicative variables are used in order to define dynamics phases of lithium electrode (in black on the figure), electrolyte (green) and two SEI domains (blue and red) and their interaction. This method allows to consider the SEI as a multi-domains object, where each region has its own (chemical, mechanical and ion transport) properties. Our results show that a smaller current density result in homogeneous deposition (top row on the figure), where a high current leads to a fracture of the SEI and a dendrite growth (bottom row). We highlighted the influence of SEI properties such as the thickness, the ratio between SEI domains or the surface tension on the deposition dynamic.On the left of the figure, the simulation box constituted of lithium (in black color) in contact with a solid electrolyte interphase constituted of a dense (blue) and porous (red) SEI, and electrolyte (green). The dynamic evolution of lithium and SEI, under low and high current density 0.12 and 12 mA/cm² are reported on top and bottom figures respectively.

Lithium Abundances from the LAMOST Medium-resolution Survey Data Release 9

Lithium is a fragile but crucial chemical element in the Universe, and exhibits interesting and complex behaviors. Thanks to the mass of spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey (MRS), we can investigate the lithium abundances in a large and diverse sample of stars, which could bring vital help in studying the origin and evolution of lithium. In this work, we use the Li i 6707.8 Å line to derive the lithium abundance through a template-matching method. A catalog of precise lithium abundance is presented for 795,384 spectra corresponding to 455,752 stars from the LAMOST MRS Data Release 9. Comparing our results with those of external high-resolution references, we find good consistency with a typical deviation of σ A(Li) ∼ 0.2 dex. We also analyze the internal errors using stars that have multiple LAMOST MRS observations, which will reach as low as 0.1 dex when the signal-to-noise ratio of the spectra is >20. Besides, our result indicates that a small fraction of giant stars still exhibit a surprisingly high lithium content, and 967 stars are identified as Li-rich giants with A(Li) > 1.5 dex, accounting for ∼2.6% of our samples. If one takes into account the fact that nearly all stars deplete lithium during the main sequence, then the fraction of Li-rich stars may far exceed 2.6%. This new catalog covers a wide range of stellar evolutionary stages from pre-main sequence to giants, and will provide help to the further study of the chemical evolution of lithium.

The evolution of lithium in FGK dwarf stars

This work aims to investigate the behaviour of the lithium abundance in stars with and without detected planets. Our study is based on a sample of 1332 FGK main-sequence stars with measured lithium abundances, for 257 of which planets were detected. Our method reviews the sample statistics and is addressed specifically to the influence of tides and orbital decay, with special attention to planets on close orbits, whose stellar rotational velocity is higher than the orbital period of the planet. In this case, tidal effects are much more pronounced. The analysis also covers the orbital decay on a short timescale, with planets spiralling into their parent star. Furthermore, the sample allows us to study the relation between the presence of planets and the physical properties of their host stars, such as the chromospheric activity, metallicity, and lithium abundance. In the case of a strong tidal influence, we cannot infer from any of the studies described that the behaviour of Li differs between stars that host planets and those that do not. Our sample includes stars with super-solar metallicity ([Fe/H] > 0.15 dex) and a low lithium abundance (A(Li) < 1.0 dex). This enabled us to analyse scenarios of the origin and existence of these stars. Considering the possible explanation of the F dip, we show that it is not a plausible scenario. Our analysis is based on a kinematic study and concludes that the possible time that elapsed in the travel from their birth places in the central regions of the Galaxy to their current positions in the solar neighbourhood is not enough to explain the high lithium depletion. It is remarkable that those of our high-metallicity low-lithium stars with the greatest eccentricity (e > 0.2) are closest to the Galactic centre. A dedicated study of a set of high-metallicity low-Li stars is needed to test the migration-depletion scenario.

Thermal characteristic evolution of lithium–ion batteries during the whole lifecycle

This work extensively investigates the thermal characteristic evolution of lithium-ion batteries under different degradation paths, and the evolution mechanism through multi-angle characterization is revealed. Under different degradation paths, the evolution trend of temperature rise rate remains unchanged with respect to depth of discharge during the adiabatic discharge process, albeit to varying degrees of alteration. The temperature rise rate changes significantly with aging during the adiabatic discharge process under low-temperature cycling and high-rate cycling paths. The total heat generation rate, irreversible heat generation rate, and reversible heat generation rate exhibit similar evolution behavior with aging under different degradation paths. The interval range of endothermic process of reversible electrochemical reactions increases and the contribution of irreversible heat to the total heat increases with aging. To further standardize the assessment of different degradation paths on the thermal characteristics, this work introduces the innovative concept of “Ampere-hour temperature rise”. In low-temperature cycling and high-rate cycling paths, the ampere-hour temperature rise increases significantly with aging, particularly accentuated with higher discharge rates. Conversely, in high-temperature cycling and high-temperature storage paths, the ampere-hour temperature rise remains relatively stable during the initial stages of aging, yet undergoes a notable increase in the later stages of aging. The multi-angle characterization reveals distinct thermal evolution behavior under different degradation paths primarily attributed to different behavior changes of severe side reactions, such as lithium plating. The findings provide crucial insights for the safe utilization and management of lithium–ion batteries throughout the whole lifecycle.

一种三元锂电池析锂特性以及检测方法研究

一种三元锂电池析锂特性以及检测方法研究

3D Morphological Evolution of Dead and Active Lithium at the Graphite-Separator-Electrolyte Interface during Fast Charging

Lithium-ion batteries (LIBs) have profoundly advanced the development of electric vehicles (EV). However, one of the remaining bottlenecks in the widespread adoption of EVs is the long charging time required for commercial LIBs. There is a global push towards extreme fast charging (XFC) to reduce charging times to 10-15 minutes.1 However, XFC results in rapid degradation in the electrochemical performance of batteries, mainly due to Li plating. This plating refers to the loss of active Li, where it either becomes dead meaning electronically disconnected after plating on the anode, or it becomes inactive due to the irreversible reaction of Li with the electrolyte to form a solid electrolyte interphase. Dead Li contributes significantly to capacity loss during XFC;3 thus, differentiating dead and inactive from active Li is extremely important to unravel their link with battery capacity fade. However, owing to the complexity of these competing electrochemical reactions in addition to the intricacy of detecting Li at the buried graphite-separator-electrolyte interface, a comprehensive understanding of Li plating remains a challenge.In this work, we conducted non-destructive, in-situ three-dimensional (3D) characterization of dead and active Li on energy-dense graphite electrodes during XFC using high-resolution neutron micro-computed tomography (µCT). Thick or industry-relevant (negative and positive electrodes ~ 130 μm) graphite electrodes are promising battery materials because they store higher amounts of energy. However, they plate Li faster and at lower XFC cycle numbers, and hence experience higher loss in battery capacity due to Li plating.To characterize Li plating on thick graphite electrodes, we performed high-resolution neutron µCT4 (pixel size: ~ 5.74 µm; effective spatial resolution: ~10-15 µm) at the ICON beamline5 at the Swiss Spallation Neutron Source at the Paul Scherrer Institute. Neutron µCT was used because it provides high relative neutron contrast between Li and C (~ 71.87: 5.55 barns6) for in-situ 3D imaging. Therefore, to leverage high-resolution neutron µCT for in-situ Li detection, we designed a neutron-friendly LIB. Our designed battery enabled excellent neutron transmission at the graphite-separator-electrolyte interface while exhibiting similar XFC performance at a 6C charging-rate between 3.0 and 4.1V. We imaged three batteries in the charged and discharged states under the following conditions: 4 cycles at 1C charging; 4 and 6 cycles at 6C charging. Here, we note that since inactive Li was below the spatial resolution of the ICON beamline, only dead, active, and plated Li were investigated in this work.Our results reveal changes in dead Li morphologies from isolated deposits after 4 cycles at 1C charging to increasingly mossy-like dense deposits covering the entire circumference of the graphite electrode after 6 cycles at 6C charging. Furthermore, as the XFC cycle number increased from four to six at 6C charging, the amount of dead Li increased significantly. After 6 cycles at 6C charging, we also observed dead Li outgrowths in a circular geometry onto the separator around the graphite electrode. Using our imaging data, we determined a quantitative link between the amounts of dead and active Li with the capacity loss of the battery. Our analysis suggests that the amounts of plated and dead Li increase with the charging rate and cycle number. Finally, we developed quantitative relationships in 3D between the amounts of dead, active, and plated Li, and XFC-related capacity loss of the battery.In conclusion, this work contributed to the advanced understanding of the morphological evolution of dead, active, and plated Li and their relationship with XFC-related capacity loss on thick graphite electrodes. We believe these insights will help inform rational 3D designs of thick graphite electrodes that will minimize Li plating in fast-charged LIBs.

(Battery Division Early Career Award Sponsored by Neware Technology Limited) Understanding Interfacial Mechanisms that Govern Performance in Solid-State Batteries

Solid-state batteries offer the promise of improved energy density and safety compared to lithium-ion batteries. Here, I will present our emerging understanding of the key differences between how high-capacity anode materials behave in solid-state batteries compared to in conventional liquid-electrolyte batteries. The electro-chemo-mechanical evolution of materials at solid-solid electrochemical interfaces is different than at solid/liquid interfaces, and contact evolution in particular plays a critical role in determining the behavior of solid-state batteries. I will focus on mechanisms governing lithium metal anodes (including lithium in the “anode-free” configuration) and alloy anodes. Lithium metal anodes in solid-state batteries are intrinsically limited by void formation during stripping and dendrite growth during plating. Anode-free solid-state batteries, in which there is no initial lithium metal at the anode interface, offer extremely high energy density, but there is a lack of understanding of how their behavior differs from excess-lithium electrodes. Using X-ray tomography, cryo-FIB, and finite-element modeling, we show that anode-free solid-state batteries are intrinsically limited by current concentrations at the end of stripping due to localized lithium depletion. This causes accelerated short circuiting compared to lithium-excess cells. Based on these results, the beneficial influence of metal alloy interfacial layers on controlling lithium evolution and mitigating contact loss from localized lithium depletion, including at low stack pressures, will be discussed. X-ray tomography is further shown to be particularly useful in observing the dynamic evolution of lithium metal, including void formation and filament growth. The second part of the talk focuses on alloy anodes. Alloy anodes typically exhibit fast capacity decay in lithium-ion batteries because of excessive solid-electrolyte interphase growth. We show that alloy anodes in solid-state batteries can exhibit improved interfacial stability and enhanced cyclability. Furthermore, in situ measurement of stack pressure evolution during cycling shows that the volume changes of alloy anodes can lead to large pressure swings within the cell, giving insight into electrode composite evolution. Based on these insights, we present a new design for dense foil alloy anodes. This design offers a paradigm that does away with slurry coating, potentially reducing manufacturing costs. Taken together, these findings show the importance of controlling chemo-mechanics and interfaces in solid-state batteries for improved energy storage capabilities.

G–C3N4–assisted synthesis of ultrafine Mn2O3 nanoparticles embedded into N–doped carbon for advanced lithium–ion battery anode

The construction of advanced transition metal oxide (TMO)/carbon anodes to substitute graphite is always being an enormous challenge for the evolution of lithium–ion batteries (LIBs). Herein, a g–C3N4–assisted pyrolysis strategy is exploited to produce Mn2O3 nanoparticles embedded into N–doped carbon (Mn2O3@NC) hybrids. The results confirm that g–C3N4 plays three critical roles (dispersing agent, pore–forming agent and doping agent) in producing Mn2O3@NC hybrids. In the meantime, it is verified that the feed of Mn source greatly affects the synthesis of Mn2O3@NC hybrids. As a consequence, the resultant Mn2O3@NC–M (M means medium loading of Mn source) reaches a balanced proportion of Mn2O3 and NC, and contemporaneously displays a series of intriguing features, including ultrafine Mn2O3 nanoparticles, large specific surface area, rich mesopores and much high N doping amount. Benefitting from these advantages, the obtained Mn2O3@NC–M shows much enhanced cycling stability and rate performance when engaged as an battery anode.

Lithium Evolution in the Low-mass Evolved Stars with Asteroseismology and LAMOST Spectroscopy

Lithium Evolution in the Low-mass Evolved Stars with Asteroseismology and LAMOST Spectroscopy

Phase-Field Modeling of Dead Lithium Formation during Charge/Discharge Cycles

The formation of inactive or "dead" lithium is one of the main reasons for performance decay in lithium batteries, but recent studies find that modified charging protocols can revive this inactive portion of lithium. Thus, the ability to simulate events that lead to the disconnection and reconnection of lithium under experimental conditions can provide a fundamental understanding of the evolution of dead lithium during the charge/discharge cycle. Here, we apply a recently developed quantitative electrochemical phase-field model to study the morphological and topological evolution of lithium during battery operation. We simulate the charge/discharge behavior of lithium metal anodes from the scale of individual dendrites to anodes of relevant experimental size with realistic materials parameters to examine the pathways leading to disconnection and reconnection. Additionally, we quantify the amount of inactive lithium formed during cycling. We discuss the effect of various factors like electrolyte properties, discharge rate, and the assumed reaction kinetics (i.e., Butler-Volmer versus Marcus-Hush) on dead lithium formation. The presented simulation tool can be employed to explore battery design; thus, we will discuss possible ways to optimize the charge and discharge cycles to minimize the amount of dead lithium. Beyond the present application to lithium, the model can also be extended to other metal-anode batteries.

Salt–template assisted fabrication of Co3O4 nanodots anchored into 2D N–doped carbon nanosheets as an advanced anode for lithium–ion batteries

The design and exploitation of advanced transition metal oxides (TMO)/carbon hybrid anodes remain significant but challenging for the evolution of lithium–ion batteries (LIBs). In this work, Co3O4 nanodots anchored into 2D N-doped carbon nanosheets (Co3O4 NDs/NCN) hybrid is successfully fabricated by a facile salt-template assisted pyrolysis strategy using glucose, Co(NO3)2·6H2O and NaCl salt template as reaction precursors. The morphology, structure and composition of the resultant Co3O4 NDs/NCN hybrid are systematically investigated, and the effect of salt template on the preparation of products is also deeply explored. It is surprisingly found that the introduction of NaCl template promotes the formation of Co3O4, which is different from what has been reported previously. In addition, the added NaCl template can be used to regulate the microstructure of Co3O4 NDs/NCN hybrid, which displays unique micromorphology (Co3O4 NDs anchored into 2D NCN), successful N doping in carbon matrix, Co-N-C bond between two components and much increased specific surface area. As a result, this hybrid shows excellent lithium storage performance when used as the anode for LIBs, which can be comparable to those previously reported Co3O4/C hybrid anodes. Clearly, this work offers a good reference for the construction of low-cost and high-performance TMO/carbon LIBs anodes.

The role of radial migration on tracing lithium evolution in the Galactic disc

ABSTRACTWith the calculated guiding centre radius Rguiding and birth radius Rbirth, we investigate the role of radial migration on the description of lithium evolution in the Galactic disc based on the upper envelope of the A(Li) versus [Fe/H] diagram. Using migration distances, we find that stars in the solar neighbourhood are born at different locations in the Galactic disc, and cannot all be explained by models of chemical evolution in the solar neighbourhood. It is found that the upper envelope of the A(Li) versus [Fe/H] diagram varies significantly with Rbirth, which explains the decrease of Li for super-metal-rich (SMR) stars because they are non-young stars born in the inner disc. The upper envelope of Li-Rbirth plane fits very well with chemical evolution models by Grisoni et al. for Rbirth = 7–12 kpc, outside which young stars generally lack sufficient time to migrate to the solar neighbourhood. For stars born in the solar neighbourhood, the young open clusters and the upper envelope of field stars with age <3 Gyr fit well with theoretical prediction. We find that calculations using stars with ages less than 3 Gyr are necessary to obtain an undepleted Li upper envelope, and that stars with solar age (around 4.5 Gyr) have depleted around 0.3 dex from the original value based on the chemical evolution model of Grisoni et al.