Lithium Loss Research Articles

Development and Verification of a Diagnostic Technology for Waste Battery Deterioration Factors.

We defined four major deterioration factors (electrolyte loss (EL), lithium loss (LL), lithium precipitation (LP), and compound deterioration (CD)). Then, we derived eleven key performance indicators (KPIs) for comparative analysis. After that, we fabricated three deteriorated cells for each of three deterioration factors (EL, LL, and LP) and one cell with CD (for verification) with four individual (dis)charging experiment manuals. The two major contributions of this study are the performance of 1)trend analysis to determine a suitable diagnostic metric by inspecting the eleven KPIs and 2) comparison analysis of [[EQUATION]]and [[EQUATION]]to verify the effectiveness of utilizing [[EQUATION]]as a real-time deterioration diagnostic factor using a concept of model-in-the-loop simulation. The results show that 1) [[EQUATION]]has the most conspicuous trendline tendency among the eleven comparison targets for all four major deterioration factors, and 2) the angle difference between the two trends of [[EQUATION]]and [[EQUATION]]lies within a minimum of 9° and a maximum of 43° (with a 104scale on the x-axis and a 10-7scale on the y-axis for a clear trend line analysis). From this, we can conclude that the trendline-based real-time deterioration analysis employing [[EQUATION]]may be practically applicable to a limited extent.

Electrochemically pre-lithiated SiO2@C nanocomposite anodes for improved performance in lithium-ion batteries

Silica (SiO2)-based materials are a promising alternative anode material due to their high specific capacity, abundance, safety, and environmental friendliness. However, the significant volume expansion and the formation of a solid electrolyte interphase (SEI) with electrolytes cause active lithium loss and result in poor Coulombic efficiency of SiO2-based materials, which hinder their commercial applications. Therefore, pre-lithiation, a method of embedding extra lithium ions in the electrodes prior to cycling, is an effective approach to replenish the largely irreversible lithium loss during cycling and overcomes these challenges. In this study, carbon-coated silica (SiO2@C) nano composite was synthesized via a sol–gel method and the beneficial impacts of using pre-lithiated SiO2@C electrodes in coin cells were investigated. It is shown that the carbon coating onto the surface of the SiO2 particles and the pre-lithiation method led to a distinct improvement in the overall capacity and Coulombic efficiency of the cells due to the pre-formed SEI and the presence of a lithium reservoir within the anode. Furthermore, the anodes exhibited excellent cycling stability and good rate capability up to 2 A g−1.

Overlithiation-driven structural regulation of lithium nickel manganese oxide for high-performance battery cathode

Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material due to its high operation voltage, cobalt free nature and low cost. High energy density of batteries could be realized by coupling LNMO with high-capacity Si based anodes, before which large active lithium loss at the anode should be addressed. Pre-insertion of additional lithium (Li, x) into LNMO, namely overlithaition of LNMO (L1+xNMO) here, becomes a promising approach for active Li compensation. Understanding the materials structure and property evolution of L1+xNMO and their further effect on electrochemical behavior is crucial. Although spinel LNMO could endure a certain amount of extra Li, its excessive insertion could cause degradation in materials structure, interfacial stability and electrochemical performance due to the introduction of large strain, grain boundaries and immoderate reduction of Mn element. L1.4NMO showed a tradeoff between donable lithium-ion capacity and electrochemical cycling stability among the investigated L1+xNMO (x = 0, 0.2, 0.4, 0.6 and 1) samples. L1.4NMO||Si/C cell presented a reversible capacity of 121.7 mAh g−1 and energy density of 429 Wh kg−1, achieving over 50 % improvement than that of LNMO||Si/C cell.

Synergistic effects of low - level magnesium and chromium doping on the electrochemical performance of LiNiO2 cathodes

LiNiO2 cathode materials with magnesium and chromium doping were prepared using a simple low - cost and efficient co - precipitation and lithiation procedure. During this procedure, both magnesium and chromium form a concentrated core particle, unto which nickel hydroxide precipitates. During lithiation, the elements in question will redistribute themselves and form a homogenous mixture. Magnesium - containing materials exhibit an excellent electrochemical performance, due to phase stabilizing effects, while for chromium - containing materials, performance remains poor. Rietveld refinement reveals that there is a possible upper limit for Mg doping (~ 2.5 mol %) as a pilar dopant. Washing of the lithiated materials was explored, and it is proposed that this can improve capacity retention in prolonged cycling. However, the inevitable loss of lithium from the surface layer remains a challenge. Two sources for the chromium facilitated capacity decay are proposed, both owing to the highly irreversible redox reaction of hexavalent chromium possibly blocking lithium pathways.

Research on the impact of high-temperature aging on the thermal safety of lithium-ion batteries

Understanding the thermal safety evolution of lithium-ion batteries during high-temperature usage conditions bears significant implications for enhancing the safety management of aging batteries. This work investigates the thermal safety evolution mechanism of lithium-ion batteries during high-temperature aging. Similarities arise in the thermal safety evolution and degradation mechanisms for lithium-ion batteries undergoing cyclic aging and calendar aging. Employing multi-angle characterization analysis, the intricate mechanism governing the thermal safety evolution of lithium-ion batteries during high-temperature aging is clarified. Specifically, lithium plating serves as the pivotal factor contributing to the reduction in the self-heating initial temperature. Additionally, the crystal structure of the cathode induced by the dissolution of transition metals and the reductive gas generated during aging attacking the crystal structure of the cathode lead to a decrease in thermal runaway triggering temperature. Furthermore, the loss of active materials and active lithium during aging contributes to a decline in both the maximum temperature and the maximum temperature rise rate, ultimately indicating a decrease in the thermal hazards of aging batteries.

Investigation of the Influence of Silicon Oxide Content on Electrolyte Degradation, Gas Evolution, and Thickness Change in Silicon Oxide/Graphite Composite Anodes for Li-Ion Cells Using Operando Techniques

This research paper investigates the influence of varying silicon oxide (SiOx) content on the performance and aging of lithium-ion cells. In-depth investigations encompass charge and discharge curves, thickness changes, electrolyte degradation, gas evolution, and chemical analysis of cells with different silicon oxide proportions in the anode and their associated cathodes. The results show that a higher silicon oxide content in the anode increases the voltage hysteresis between charge and discharge. Moreover, the first-cycle efficiencies decrease with a higher silicon oxide content, attributed to irreversible LixSiy formation and the subsequent loss of active lithium from the cathode during formation. The anodes experience higher thickness changes with increased silicon oxide content, and peaks in differential voltage curves can be correlated with specific anode active materials and their thickness change. A gas analysis reveals conductive salt and electrolyte intermediates as well as silicon-containing gaseous fragments, indicating continuous electrolyte decomposition and silicon oxide aging, respectively. Additionally, a chemical analysis confirms increased silicon-derived products and electrolyte degradation on electrode surfaces. These findings underscore the importance of a holistic aging investigation and help understand the complex chemical changes in electrode materials for designing efficient and durable lithium-ion cells.

Interphase Engineering Enhanced Electro-chemical Stability of Prelithiated Anode.

Prelithiation is an essential technology to compensate for the initial lithium loss of lithium-ion batteries due to the formation of solid electrolyte interphase (SEI) and irreversible structure change. However, the prelithiated materials/electrodes become more reactive with air and electrolyte resulting in unwanted side reactions and contaminations, which makes it difficult for the practical application of prelithiation technology. To address this problem, herein, interphase engineering through a simple solution treatment after chemical prelithiation is proposed to protect the prelithiated electrode. The used solutions are carefully selected, and the composition and nanostructure of the as-formed artificial SEIs are revealed by cryogenic electron microscopy and X-ray photoelectron spectroscopy. The electrochemical evaluation demonstrates the unique merits of this artificial SEI, especially for the fluorinated interphase, which not only enhances the interfacial ion transport but also increases the tolerance of the prelithiated electrode to the air. The treated graphite electrode shows an initial Coulombic efficiency of 129.4%, a high capacity of 170 mAh g-1 at 3 C, and negligible capacity decay after 200 cycles at 1 C. These findings not only provide a facile, universal, and controllable method to construct an artificial SEI but also enlighten the upgrade of battery fabrication and the alternative use of advanced electrolytes.

Revealing the degradation behaviors and mechanisms of NCM cathode in scrapped lithium-ion batteries

Existing research has predominantly studied the typical degradation mechanisms of cathodes under accelerated aging conditions in laboratory settings. However, the degradation mechanisms of cathodes from scrapped lithium-ion batteries (LIBs) require more attention due to significant differences in working conditions between actual and laboratory levels. In this work, we systematically investigated the deterioration behaviors and degradation mechanisms of scrapped LiNi0.5Co0.2Mn0.3O2 (SNCM) from commercial LIBs, comparing it with pristine LiNi0.5Co0.2Mn0.3O2 through characterizations and electrochemical tests. Results indicated that SNCM particles were severely disintegrated into scattered primary particles due to altered lattice parameters, which is one of the main reasons for degradation. Furthermore, the surface layer of SNCM experienced significant phase transformations with varying proportions of transition metals in different valence states, while bulk structure of SNCM remained unchanged. Lithium loss, a small amount of transition metals, and thereby a high degree of cation mixing in SNCM are the other degradation factors. It was found that SNCM demonstrated poor electrochemical performance with only 111.8 m Ah g−1 of initial discharge capacity and 50.9% capacity retention after 100 cycles at 0.5C. This work pertinently focused on the degradation mechanisms of SNCM, offering perspectives for improving battery lifespan and regenerating SNCM through appropriate measures.

Scavenging of “Dead Sulfur” and “Dead Lithium” Revealed by Integrated–Heterogeneous Catalysis for Advanced Lithium–Sulfur Batteries

AbstractThe simultaneous engineering of sulfur cathode and Li anode is critical for electrolyte‐starved high energy density Li–S batteries, in which slow electrochemical conversions and side chemical reactions of dead sulfur are found to be the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li–S batteries. Herein, this work challenges the conventional wisdom of heterogeneous and homogeneous catalyses in Li–S batteries and proposes the concept of integrated–heterogeneous catalysis to simultaneously scavenge the dead sulfur and dead lithium to compensate the active materials sulfur and lithium loss simply through adding a small amount of ZnI2 into conventional electrolyte of Li–S cells. Regulated by integrated–heterogeneous catalysis, over 1300 h of cycling is realized in Li||Li symmetric cells, revealing superb compatibility of the ZnI2‐incorporated electrolyte with lithium metal. Meanwhile, the ZnI2 shows good prospects in promoting the reutilization of dead sulfur in both theoretical calculation and experimental tests. Practically, a high initial capacity of 1170 mAh g−1 with decent cycling stability is achieved in electrolyte‐starved and high‐loading pouch cells (5.0 µL mg−1 and 5.2 mg cm−2).

(Digital Presentation) Approaches of Pre-Lithiation on Si Anode for Lithium-Ion Batteries

Silicon is one of the most attractive anode materials for next generation high-capacity lithium-ion batteries (LIBs) due to its high specific capacity. However, the large volume change (up to 300%) of silicon during lithiation/delithiation process leads to coupled mechanical and chemical degradation, such as pulverization of silicon particles, formation of unstable solid-electrolyte interphase (SEI), and loss of electrical connectivity, resulting in high irreversible capacity loss and rapid capacity fading. Pre-lithiation is one of the effective approaches to compensate for the loss of active lithium and extend battery cycle life. In this work, various approaches of pre-lithiation for Si electrodes are systematically studied and compared. Different levels of pre-lithiation dosage are applied to the Si electrodes and the pre-lithiated Si electrodes are evaluated in NMC622/Si full cell configuration. After pre-lithiation, the cell capacity and cycling stability are significantly improved. The impacts of operating voltage window, and N/P ratio on electrochemical performance are also investigated. The morphology of pre-lithiated Si electrodes before and after cycling are also compared via cross section scanning electron microscopy (SEM) to understand the electrode expansion and SEI formation/growth during cycling.

Modeling Electrochemical Migration and Growth of Isolated Metal Particles

Electrokinetic phenomena within complex structures are relevant in microfluidics. For example, ion concentration polarization is used for electrokinetic trapping for enhanced biosensing using molecular probes1. Concentration polarization near ion-selective membranes also plays an important role in separation systems for desalination2. Aside from microfluidics, electrochemical growth-dissolution phenomenon has been reported in lithium ion battery systems where lithium plating and subsequent growth of dendrites can exacerbate the loss of cyclable lithium through the formation of isolated Lithium (i-Li) islands3. Initially thought to be “dead”, these islands were shown to migrate from one electrode to the other through a deposition-dissolution mechanism3.We present a mathematical solution for the growth and migration of an electrochemically active metal particle in a background current. A broad range of phenomena such as viscous fingering4, diffusion-limited aggregation4 and electrochemical deposition5 follow Laplacian growth and have been traditionally described using conformal map-dynamics in two dimensions. Some non-Laplacian phenomena like electrochemical transport6,7 and advection-diffusion-limited aggregation6 fall into the conformally invariant category8 and can still be simplified using conformal-mapping techniques. Our solution applies conformal mapping to the non-Laplacian growth of the metal particle to evaluate the role of particle morphology in the evolution of the phase boundary. In addition to migration, dissolution-deposition was found to lead to formation of cusps on the phase boundary under certain conditions. The solution is applicable for a general class of problems with a reactive post or particle in an applied background flux. Analytical solutions such as the one presented here are expected to augment numerical simulations and lead to expressions that capture conditions for the onset of morphological instabilities. References S. Park, B. Sabbagh, R. Abu-Rjal, and G. Yossifon, Lab Chip, 22, 814–825 (2022) https://pubs.rsc.org/en/content/articlehtml/2022/lc/d1lc00864a.D. Deng et al., Desalination, 357, 77–83 (2015).F. Liu et al., Nature 2021 600:7890, 600, 659–663 (2021) https://www.nature.com/articles/s41586-021-04168-w.J. Mathiesen, I. Procaccia, H. L. Swinney, and M. Thrasher, Europhys Lett, 76, 257 (2006) https://iopscience.iop.org/article/10.1209/epl/i2006-10246-x.D. A. Kessler, J. Koplik, and H. Levine, http://dx.doi.org/10.1080/00018738800101379, 37, 255–339 (2006) https://www.tandfonline.com/doi/abs/10.1080/00018738800101379.M. Z. Bazant, J. Choi, and B. Davidovitch, Phys Rev Lett, 91, 045503 (2003) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.91.045503.Z. Gu et al., Phys Rev Fluids, 7, 033701 (2022) https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.7.033701.M. Z. Bazant, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 460, 1433–1452 (2004) https://royalsocietypublishing.org/doi/10.1098/rspa.2003.1218.

Ceramic Fillers for Improved Lithium-Sulfur Batteries

With the decarbonization of transportation, the demand for electric vehicles (EVs) and batteries that can power these EVs has been increasing. Lithium-ion-based batteries are already well-established and are considered the main chemistries to power current EVs. However, limited specific energy (< 300 Wh/kg) prevents these batteries from having high mileage vehicles. Lithium-sulfur batteries are considered the most promising next-generation energy storage system as they high theoretical capacity (~1675 mAhg-1), low cathode materials cost, and cell energy densities that can exceed 700 Wh/kg [1,2]. However, some major drawbacks prevent the Li-S battery system from being applicable in energy devices and hinder its commercialization, that include low power density and rapid capacity degradation during their cycling life. In addition, the lithium metal anode in Li-S batteries bring various issues to the forefront such as continuous solid electrolyte interface growth, dendrite formation, and loss of active lithium and electrolyte. These issues are further exacerbated at high C-rates which increases the possibility of an internal short-circuit and sudden cell failure [3]. In order to promote longer life cycles and prevent sudden cell failure, a thorough understanding of the cell’s electrochemical behavior is crucial for the development of a stable and practical Li-S battery system. The introduction of oxide fillers such TiO2, Al2O3, SiO2, etc. has been previously studied in various lithium-ion systems and has been shown to improve the cell’s lithium-ion transport properties, which in turn improve the performance of Li-S cells [4]. When used as interlayers they can also trap soluble polysulfides diffusing out of the cathode and reduce their crossover to the anode which helps reduce the shuttle effect of said polysulfides.In the present study, the use of a polysulfide immobilizing system to reduce sulfur loss and improve capacity retention has been demonstrated. The galvanostatic charge-discharge cycling study shows that cells retain higher capacity during the course of cycling. The initial capacity for Li-S cells with the filler average 1300+ mAh/g (C/10) while the capacity stabilizes around 1000 mAh/g after 3 cycles (C/5). The capacity retention at C/5 after 75 cycles was approximately 875 mAh/g which represents a rate 0.17% drop per cycle. When compared to control cells, the cells containing no fillers had lower initial capacity that averaged 1050 mAh/g and that rapidly declined to stabilize around 650 mAh/g. However, after this major drop, the cells remained stable no with measurable drop after 75 cycles. The behavior indicates that the cells with fillers delayed the effect of sulfur loss experienced in cells without fillers; however, the slow capacity drop that ensued, indicates that while polysulfide trapping was efficient it was unable to fully prevent it. The effect of fillers on the Coulombic efficiency (CE) also supports the polysulfide “trapping” mechanism and shows the ability of the cell to reduce the shuttle effect that contributes to lower CE values. Further electrochemical studies have been performed to understand the mechanisms of the improvement of the cell.

Utilizing Bayesian Optimization to Facilitate Differential Voltage Analysis of Lithium Ion Batteries

Differential voltage analysis (DVA) is a non-destructive, in situ method for analyzing degradation in lithium ion (Li-ion) batteries, and can be used to identify major modes of performance degradation, such as loss of lithium inventory (LLI) and loss of active material (LAM). Using the cycling voltage derivative with respect to capacity of half cells and full cells, DVA can be used to estimate which mode is the main contributor to degradation. Analysis of the signature peaks in the half cell to the full cell can reveal the degradation mode of full cell. Shifts in the peak can indicate LLI, while intensification and narrowing of peaks can indicate LAM. Analyzing the peak changes after cycling allows quantitative determination of how much cell aging has occurred, and what mode is involved in the cell aging process. However, the process of analyzing peak changes manually is inefficient and time consuming. In this work, we utilize a Bayesian optimization approach to facilitate the process of fitting full cell DVA data with pristine half-cell data. The Bayesian optimization algorithm finds the best deformation of pristine half-cell data to fit full-cell data automatically and efficiently for multiple chemistries. The only manual procedures for each fitting are reading data files into the program and determining a coarse bound. The rest is automated and takes less than ten minutes for each fitting. The fitting accuracy is comparable to manual fitting and significantly less time consuming. This method facilitates battery aging analysis and can be generalized to different kinds of data sets as well.

Strategies of Practical Implementation of Chemical Pre-Lithiation Using Lithium Arene Complex Solutions: A Systematic Study on Silicon-Based Anodes

Currently, Lithium ion batteries (LIBs) are state-of-the-art (SOTA) energy storage systems. There is an urgent need for further improvements in terms of gravimetric and volumetric energy of LIBs, for a successful market penetration of electric vehicles. Therefore, development of advanced negative electrode materials is of high interest. Here, silicon (Si) is a promising active material to replace SOTA graphite due to its ~10-fold higher specific capacity and being also high abundant.However, Si undergoes severe volume changes up to 280% during (de-)lithiation, resulting in fast capacity fading and short cycle life due to the continuous re-formation of the solid electrolyte interphase (SEI), leading to active lithium losses (ALL). In order to counteract ALL, research is focusing on suitable pre-lithiation processes. Among different pre-lithiation methods, chemical pre-lithiation by application of lithium arene complex (LAC) solutions is promising as it is a fast, easy and cost-effective method.In this work, the stability of three different solvents to produce a 4,4’-dimethylbiphenyl (4,4’-DMBP) LAC is investigated via solid phase microextraction gas chromatography-mass spectrometry method (SPME-GC-MS). The optimized LAC solution is used to evaluate the stability of different binder systems with respect to electrode manufacturing. Based on these fundamental insights, different parameters such as the reaction temperature (T) and pre-lithiation time (PL-t) are systematically investigated regarding suitable degrees of pre-lithiation (DOPL) of the negative electrode. DOPLs up to a plateau of 55% can be obtained by using 0.5 M 4,4’-DMBP in tetrahydrofuran (THF) as LAC solution. Higher temperature during the reaction reduces the PL-t until achieving a pre-lithiation plateau. The impact of the parameters T and PL-t towards the electrochemical performance of Si-based LIB full cells is thoroughly investigated. It is shown that this approach improves the cycle life of a silicon nanowire graphite composite negative electrode up to 600% compared to the pristine electrodes

(Digital Presentation) Ex Situ Electrochemical Pre-Lithiation of Silicon for Lithium-Ion Battery Anodes

Crystalline silicon as an anode material for lithium-ion batteries (LIBs) has a theoretical capacity greater than 3600 mAh/g, an order of magnitude larger than the current anode materials of choice, graphite (~370 mAh/g). However, the use of silicon is hampered by several issues that hinder its widespread usage in LIBs. Chief among these is the large volume expansion that accompanies lithiation (>300%), which results in the self-pulverization of silicon during cycling and the degradation in stability and performance that accompanies it. Silicon also suffers from active lithium loss in its first cycle from the formation of Li x Si and the solid-electrolyte interphase (SEI), which irreversibly consumes lithium and decreases gravimetric/volumetric capacity (typically >20% capacity loss after the formation cycle). This capacity loss coupled with mechanical and chemical degradation leads to poor capacity retention and short cycle life. Pre-lithiation of silicon and other potential anode materials (e.g. SiOx), a process of inserting additional Li into Si prior to battery operation, is thus desired to compensate for lithium consumption and to maintain the high capacity associated with silicon. Here, we demonstrate a simple and scalable method for the ex situ (i.e. outside the cell) electrochemical synthesis of pre-lithiated silicon. In this method, a current is driven though an electrochemical stir-tank reactor composed of Si powder in electrolyte suspension and a Li containing anode. When Si particles contact the conductive inner surface of the reaction vessel, lithium ions in the electrolyte are reduced on the surface to form lithium-silicon compounds. The degree of lithiation is controlled by the applied current density, applied voltage, and/or runtime. This talk will describe the chemical and structural characteristics of pre-lithiated silicon synthesized with this technique, basic electrochemical properties of our lithiated material, and the specific advantages presented by the method vs other methods.

Effects of Lithium Metal Storage Environment on Its Reactivity toward Polyethylene Oxide-Based Blend Electrolytes.

Lithium metal has generated significant interest as an anode material because of its high theoretical capacity. However, issues such as dendrite growth and lithium loss during cycling make this material incompatible with liquid electrolytes. Solid polymer electrolytes (SPE) have been proposed as replacements as they are non-flammable, resist dendrite growth, have decent ionic conductivity, and have low resistance with lithium metal. Passivation layers, which form on the lithium metal surface and are hence intrinsic to its chemical composition, are often overlooked. Residual quantities of atmospheric gases are present in lithium metal storage environments, making surface modification and its subsequent impact on anode reactivity inevitable. Moreover, the impact of this phenomenon in a realistic lithium metal anode (LMA) environment with SPE has not yet been extensively investigated. In this study, the impact of gas exposure on an LMA was investigated by exposing freshly cut lithium rods to O2, CO2, and N2. Passivation layers were characterized via X-ray photoelectron spectroscopy. The effect of passivation layer formation on LMA reactivity toward SPE was measured by exposing passivated samples to common SPE materials. The resultant interface was characterized using Raman spectroscopy. SPE-passivation layer reactivity was correlated to ageing by electrochemical impedance spectroscopy and kinetic charge transfer via galvanostatic linear polarization at the LMA-SPE interface in symmetric Li─SPE─Li stacks. This study revealed that the chemical composition of the passivation layer affects LMA reactivity toward SPE and electrochemical performance. A thorough characterization of the lithium metal passivation layer is essential to understanding the fundamental factors affecting solid-state lithium metal battery performance.

Lithium Iron Phosphate and Layered Transition Metal Oxide Cathode for Power Batteries: Attenuation Mechanisms and Modification Strategies.

In the past decade, in the context of the carbon peaking and carbon neutrality era, the rapid development of new energy vehicles has led to higher requirements for the performance of strike forces such as battery cycle life, energy density, and cost. Lithium-ion batteries have gradually become mainstream in electric vehicle power batteries due to their excellent energy density, rate performance, and cycle life. At present, the most widely used cathode materials for power batteries are lithium iron phosphate (LFP) and LixNiyMnzCo1-y-zO2 cathodes (NCM). However, these materials exhibit bottlenecks that limit the improvement and promotion of power battery performance. In this review, the performance characteristics, cycle life attenuation mechanism (including structural damage, gas generation, and active lithium loss, etc.), and improvement methods (including surface coating and element-doping modification) of LFP and NCM batteries are reviewed. Finally, the development prospects of this field are proposed.

Modeling and application of continuous ion exchanges process for lithium recovery from salt lake brine

A composite model has been developed to simulate and optimize the continuous multi-column lithium adsorption based on the continuous adsorption of lithium from high Mg/Li ratio brines. The model not only simulates all the adsorption columns of the adsorption process, but also the auxiliary equipment connected to the adsorption columns such as pumps and valves, to describe the multi-column continuous lithium extraction process in detail. To improve the efficiency of lithium extraction, a 4-zone, 20-column carousel-type continuous lithium extraction process was proposed and optimized using the composite model. When the feed flow rate was set to 25 mL/min in the adsorption zone, 8 mL/min in the washing zone and 15 mL/min in the product zone, the Li+ extraction rate in the adsorption zone was 98.26%, the lithium loss in the washing zone was 16.12%, the magnesium removal rate in the washing process was 98.77%, the concentration of lithium solution obtained in the product zone was 488.55 mg/L, and the magnesium-lithium ratio was 6.45, with a lithium recovery of 79.68% for the whole continuous lithium extraction process. Overall, the continuous carousel lithium extraction process achieved the expected magnesium separation and continuous lithium extraction from the brine of the Qarhan Salt Lake.

Perspective on the mechanism of mass transport-induced (tip-growing) Li dendrite formation by comparing conventional liquid organic solvent with solid polymer-based electrolytes

A major challenge of Li metal electrodes is the growth of high surface area lithium during Li deposition with a variety of possible shapes and growing mechanisms. They are reactive and lead to active lithium losses, electrolyte depletion and safety concerns due to a potential risk of short-circuits and thermal runaway. This work focuses on the mechanism of tip-growing Li dendrite as a particular high surface area lithium morphology. Its formation mechanism is well-known and is triggered during concentration polarization, i.e. during mass (Li+) transport limitations, which has been thoroughly investigated in literature with liquid electrolytes. This work aims to give a stimulating perspective on this formation mechanism by considering solid polymer electrolytes. The in-here shown absence of the characteristic “voltage noise” immediately after complete concentration polarization, being an indicator for tip-growing dendritic growth, rules out the occurrence of the particular tip-growing morphology for solid polymer electrolytes under the specific electrochemical conditions. The generally poorer kinetics of solid polymer electrolytes compared to liquid electrolytes imply lower limiting currents, i.e. lower currents to realize complete concen­tration polarization. Hence, this longer-lasting Li-deposition times in solid polymer electro­lytes are assumed to prevent tip-growing mechanism via timely enabling solid electrolyte interphase formation on fresh Li deposits, while, as stated in previous literature, in liquid electrolytes, Li dendrite tip-growth process is faster than solid electrolyte interphase forma­tion kinetics. It can be reasonably concluded that tip-growing Li dendrites are in general practically unlikely for both, (i) the lower conducting electrolytes like solid polymer electro­lytes due to enabling solid electrolyte interphase formation and (ii) good-conducting electro­lytes like liquids due to an impractically high current required for concentration polarization.

Lithiophilic composite solid electrolyte interphase layer modified Li foils: Li metal battery failure analysis

Li metal battery with higher energy density becomes increasing important to reach a carbon neutrality society. However, the usage of Li metal is usually failed due to the side-reactions, dendrite formations, and volume expansion. To tackle these difficulties, artificial solid electrolyte interphase with multiple functions is proposed. In our work, a magnesium-based inorganic-organic film is coated on Li metal with tape-casting. LixMg alloy and nano-LiF particles produced after activation process can lower the nucleation energy barriers and increase the Li ion transportation. Polymer layers with high flexibility are adopted to control the volume change caused by repeatly lithium plating/stripping. As a result, the Li symmetrical cell runs stable for 1300 h with a lower over-potential of 3 mV under limited carbonate electrolyte. Li metal batteries degradation mechanism with different N/P ratio and C rates are discussed in details. The full cell with LiFePO4 and 30 μm Li foil delivers a capacity of 132 mA h g−1 after 300 cycles, the bare Li is dead after 75 cycles due to the loss of active lithium. LiNi0.6Co0.2Mn0.2O2 coupled with modified Li foil with mass loading of 1.44 mA h cm−2 is superior than bare Li at 1 C, the latter quickly die due to the dry-out of electrolyte.