This work is a simulation model with the LAMMPS calculation code of an electrode based on alkali metal oxides (lithium, sodium and potassium) using the Lennard Jones potential. For a multiplicity of 8*8*8, we studied ...This work is a simulation model with the LAMMPS calculation code of an electrode based on alkali metal oxides (lithium, sodium and potassium) using the Lennard Jones potential. For a multiplicity of 8*8*8, we studied a gap-free model using molecular dynamics. Physical quantities such as volume and pressure of the Na-O and Li-O systems exhibit similar behaviors around the thermodynamic ensembles NPT and NVE. However, for the Na2O system, at a minimum temperature value, we observe a range of total energy values;in contrast, for the Li2O system, a minimum energy corresponds to a range of temperatures. Finally, for physicochemical properties, we studied the diffusion coefficient and activation energy of lithium and potassium oxides around their melting temperatures. The order of magnitude of the diffusion coefficients is given by the relation Dli-O >DNa-O for the multiplicity 8*8*8, while for the activation energy, the order is well reversed EaNa-O > EaLi-O.展开更多
Lithium-ion batteries(LIBs)that reached their end-of-life(EoL)require recycling,rather than disposal,to recirculate valuable metals and protect the environment.This led us to investigate the extraction of metals from ...Lithium-ion batteries(LIBs)that reached their end-of-life(EoL)require recycling,rather than disposal,to recirculate valuable metals and protect the environment.This led us to investigate the extraction of metals from the cathodes of EoL lithium-titanate batteries using ethylenediaminetetraacetic acid disodium(EDTA-2Na).In this work,an orthogonal array was used to design experiments and sig-nal-to-noise calculations were used to define the optimal conditions,which were 0.50 mol/L EDTA-2Na,pH=6,75℃,180 min,2%pulp density,and 300 r/min,resulting in 97.96%,94.79%,96.45%,and 98.89%leaching efficiencies for Li,Ni,Co,and Mn,respectively.Stat-istically significant interactions between variables were then identified using Pearson’s correlation at the 95%confidence interval,and the pH and temperature were found to be significant.The extraction efficiency decreased as the pH increased,but increased as the temperat-ure increased.Machine learning fitting using linear regression for multi-output prediction was unsatisfactory,whereas random forest re-gression(RFR)produced satisfactory results.Permutation importance was computed on the fitted RFR to determine feature importance,and confirmed that the pH and temperature were influential variables;however,the time and pulp density were also noted.As the fitted RFR failed to satisfactorily predict leaching efficiencies in additional validation experiments,we recommend increasing the number of ex-periments and using additional fitting models.An additional analysis that included the initial oxidation-reduction potential(optimal 33.3 mV)revealed this to be the most important variable,the effect of which largely overshadows those of all the other variables.Finally,an environmental assessment highlighted the benefits of the chelating extraction;however,the economic assessment indicated room for improvement.展开更多
Spinel lithium manganese oxide(LiMn_(2)O_(4), LMO) emerges as a promising cathode material for future stationary energy storage applications due to its high voltage, safety, cost-effectiveness, and electrochemical per...Spinel lithium manganese oxide(LiMn_(2)O_(4), LMO) emerges as a promising cathode material for future stationary energy storage applications due to its high voltage, safety, cost-effectiveness, and electrochemical performance. However,LMO suffers from rapid capacity degradation caused by the Jahn–Teller effect, Mn dissolution and side reactions. The mechanism remains unclear and even contradictory across various studies, impeding the advancement of high-performance LMO and its widespread utilization. In this study, 14 Ah commercial-level LMO batteries were manufactured and assessed.The mechanism of capacity attenuation in cycle-aged cells at room temperature(RT, 25℃) and high temperature(HT,55℃) storage cells was systematically investigated through the application of electrochemical quantitative methods. The results indicate specific capacity losses of approximately 6.26% and 2.55% for the cathodes in RT cycle-aged cells and HT storage cells, respectively, in comparison to fresh cells. These values are lower than the 12.54% and 6.99% capacity losses observed in RT cycle-aged cells and HT storage cells. While RT cycle-aging and HT storage conditions do not lead to irreversible capacity loss on the anode side. The results suggest that the primary causes of irreversible capacity degradation are not located on the cathode or anode. Nevertheless, significant polarization arises from the continuous growth of the solid electrolyte interphase(SEI), believed to be catalyzed by Mn deposited on the anode, which is considered harmful.This study elucidates that inhibiting the dissolution of Mn from the cathode, facilitating its transport in the electrolyte,promoting its deposition on the anode, and catalyzing the decomposition of the electrolyte are crucial factors for enhancing the performance of LMO batteries.展开更多
The capacity fade of spinel lithium manganese oxide in lithium-ion batteries is a bottleneck challenge for the large-scale application.The traditional opinion is that Mn（Ⅱ） ions in the anode are reduced to the meta...The capacity fade of spinel lithium manganese oxide in lithium-ion batteries is a bottleneck challenge for the large-scale application.The traditional opinion is that Mn（Ⅱ） ions in the anode are reduced to the metallic manganese that helps for catalyzing electrolyte decomposition.This could poison and damage the solid electrolyte interface（SEI） film,leading to the the capacity fade in Li-ion batteries.We propose a new mechanism that Mn（Ⅱ） deposites at the anode hinders and/or blocks the intercalation/de-intercalation of lithium ions,which leads to the capacity fade in Li-ion batteries.Based on the new mechanism assumption,a kind of new structure with core-shell characteristic is designed to inhabit manganese ion dissolution,thus improving electrochemical cycle performance of the cell.By the way,this mechanism hypothesis is also supported by the results of these experiments.The LiMn2-xTixO4 shell layer enhances cathode resistance to corrosion attack and effectively suppresses dissolution of Mn,then improves battery cycle performance with LiMn_2O_4 cathode,even at high rate and elevated temperature.展开更多
Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical proper...Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical properties. However, these properties are limited by the rapid fading of cycling retention, particularly at high temperatures, because of the severe Mn corrosion triggered by the chemical reaction with fluoride(F-) species existing in the cell. To alleviate this issue, three types of silyl ether(Si–O)-functionalized task-specific additives are proposed, namely methoxytrimethylsilane, dimethoxydimethylsilane, and trimethoxymethylsilane. Ex-situ NMR analyses demonstrated that the Si-additives selectively scavenged the F-species as Si forms new chemical bonds with F via a nucleophilic substitution reaction due to the high binding affinity of Si with F-, thereby leading to a decrease in the F concentration in the cell. Furthermore, the addition of Si-additives in the electrolyte did not significantly affect the ionic conductivity or electrochemical stability of the electrolyte, indicating that these additives are compatible with conventional electrolytes. In addition, the cells cycled with Si-additives exhibited improved cycling retention at room temperature and 45 °C. Among these candidates, a combination of MTSi and the LMO cathode was found to be the most suitable choice in terms of cycling retention(71.0%), whereas the cell cycled with the standard electrolyte suffered from the fading of cycling retention triggered by Mn dissolution(64.4%). Additional ex-situ analyses of the cycled electrodes using SEM, TEM, EIS, XPS, and ICP-MS demonstrated that the use of Si-additives not only improved the surface stability of the LMO cathode but also that of the graphite anode, as the Si-additives prevent Mn corrosion. This inhibits the formation of cracks on the surface of the LMO cathode, facilitating the formation of a stable solid electrolyte interphase layer on the surface of the graphite anode. Therefore, Si-additives modified by Si–O functional groups can be effectively used to increase the overall electrochemical performance of the LMO cathode material.展开更多
Lithium cobalt oxide(LCO)is the dominating cathode materials for lithium-ion batteries(LIBs)deployed in consumer electronic devices for its superior volumetric energy density and electrochemical performances.The const...Lithium cobalt oxide(LCO)is the dominating cathode materials for lithium-ion batteries(LIBs)deployed in consumer electronic devices for its superior volumetric energy density and electrochemical performances.The constantly increasing demands of higher energy density urge to develop high-voltage LCO via a variety of strategies.However,the corresponding modification mechanism,especially the influence of the long-and short-range structural transitions at high-voltage on electrochemical performance,is still not well understood and needs further exploration.Based on ss-NMR,in-situ X-ray diffraction,and electrochemical performance results,it is revealed that the H3 to H1-3 phase transition dictates the structural reversibility and stability of LCO,thereby determining the electrochemical performance.The introduction of La and Al ions could postpone the appearance of H1-3 phase and induce various types of local environments to alleviate the volume variation at the atomic level,leading to better reversibility of the H1-3 phase and smaller lattice strain,and significantly improved cycle performance.Such a comprehensive long-range,local,and electronic structure characterization enables an in-depth understanding of the structural evolution of LCO,providing a guiding principle for developing high-voltage LCO for high energy density LIBs.展开更多
Herein, a facile strategy for the synthesis of sandwich pyrolyzed bacterial cellulose（PBC）/graphene oxide（GO） composite was reported simply by utilizing the large-scale regenerated biomass bacterial cellulose as p...Herein, a facile strategy for the synthesis of sandwich pyrolyzed bacterial cellulose（PBC）/graphene oxide（GO） composite was reported simply by utilizing the large-scale regenerated biomass bacterial cellulose as precursor. The unique and delicate structure where three-dimensional interconnected bacterial cellulose（BC） network embedded in two-dimensional GO skeleton could not only work as an effective barrier to retard polysulfide diffusion during the charge/discharge process to enhance the cyclic stability of the Li–S battery, but also offer a continuous electron transport pathway for the improved rate capability.As a result, by utilizing pure sulfur as cathodes, the Li–S batteries assembled with PBC/GO interlayer can still exhibit a capacity of nearly 600 mAh·g^-1 at 3C and only 0.055% capacity decay per cycle can be observed over 200 cycles. Additionally, the cost-efficient and environmentfriendly raw materials may enable the PBC/GO sandwich interlayer to be an advanced configuration for Li–S batteries.展开更多
Lithium plays an increasingly important role in scientific and industrial processes, and it is extremely important to extract lithium from a high Mg^(2+)/Li^(+) mass ratio brine or to recover lithium from the leachate...Lithium plays an increasingly important role in scientific and industrial processes, and it is extremely important to extract lithium from a high Mg^(2+)/Li^(+) mass ratio brine or to recover lithium from the leachate of spent lithiumion batteries. Conventional wisdom shows that Li^(+) with low valence states has a much weaker adsorption(and absorption energy) with graphene than multivalent ions such as Mg^(2+). Here, we show the selective adsorption of Li^(+) in thermally reduced graphene oxide(rGO) membranes over other metal ions such as Mg^(2+), Co^(2+), Mn^(2+),Ni^(2+), or Fe^(2+). Interestingly, the adsorption strength of Li^(+) reaches up to 5 times the adsorption strength of Mg^(2+),and the mass ratio of a mixed Mg^(2+)/Li^(+) solution at a very high value of 500 : 1 can be effectively reduced to 0.7 : 1 within only six experimental treatment cycles, demonstrating the excellent applicability of the rGO membranes in the Mg^(2+)/Li^(+) separation. A theoretical analysis indicates that this unexpected selectivity is attributed to the competition between cation–π interaction and steric exclusion when hydrated cations enter the confined space of the rGO membranes.展开更多
We report a “soft” graphene oxide-polymeric organosulfide nanocomposite with improved pseudocapacitive performance for high-potential（1–2.8 V vs. Li^0/Li~＋）, high-capacity（278 mAh/g） and stable（500 cycles） l...We report a “soft” graphene oxide-polymeric organosulfide nanocomposite with improved pseudocapacitive performance for high-potential（1–2.8 V vs. Li^0/Li~＋）, high-capacity（278 mAh/g） and stable（500 cycles） lithium storage.展开更多
Lithium-sulfur(Li-S) batteries are promising for high energy-storage applications but suffer from sluggish conversion reaction kinetics and substantial lithium sulfide(Li_(2)S) oxidation barrier,especially under high ...Lithium-sulfur(Li-S) batteries are promising for high energy-storage applications but suffer from sluggish conversion reaction kinetics and substantial lithium sulfide(Li_(2)S) oxidation barrier,especially under high sulfur loadings.Here,we report a Li cation-doped tungsten oxide(Li_(x)WO_(x)) electrocatalyst that efficiently accelerates the S■HLi_(2)S interconversion kinetics.The incorporation of Li dopants into WO_(x) cationic vacancies enables bidirectional electrocatalytic activity for both polysulfide reduction and Li_(2)S oxidation,along with enhanced Li^(+) diffusion.In conjunction with theoretical calculations,it is discovered that the improved electrocatalytic activity originates from the Li dopant-induced geometric and electronic structural optimization of the Li_(x)WO_(x),which promotes the anchoring of sulfur species at favourable adsorption sites while facilitating the charge transfer kinetics.Consequently,Li-S cells with the Li_(x)WO_(x) bidirectional electrocatalyst show stable cycling performance and high sulfur utilization under high sulfur loadings.Our approach provides insights into cation engineering as an effective electrocatalyst design strategy for advancing high-performance Li-S batteries.展开更多
Lithium-ion batteries(LIBs)with the“double-high”characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable electronics.However,the lithiu...Lithium-ion batteries(LIBs)with the“double-high”characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable electronics.However,the lithium ion(Li+)-storage performance of the most commercialized lithium cobalt oxide(LiCoO_(2),LCO)cathodes is still far from satisfactory in terms of high-voltage and fast-charging capabilities for reaching the double-high target.Herein,we systematically summarize and discuss high-voltage and fast-charging LCO cathodes,covering in depth the key fundamental challenges,latest advancements in modification strategies,and future perspectives in this field.Comprehensive and elaborated discussions are first presented on key fundamental challenges related to structural degradation,interfacial instability,the inhomogeneity reactions,and sluggish interfacial kinetics.We provide an instructive summary of deep insights into promising modification strategies and underlying mechanisms,categorized into element doping(Li-site,cobalt-/oxygen-site,and multi-site doping)for improved Li+diffusivity and bulkstructure stability;surface coating(dielectrics,ionic/electronic conductors,and their combination)for surface stability and conductivity;nanosizing;combinations of these strategies;and other strategies(i.e.,optimization of the electrolyte,binder,tortuosity of electrodes,charging protocols,and prelithiation methods).Finally,forward-looking perspectives and promising directions are sketched out and insightfully elucidated,providing constructive suggestions and instructions for designing and realizing high-voltage and fast-charging LCO cathodes for next-generation double-high LIBs.展开更多
Li/Ni mixing negatively influences the discharge capacity of lithium nickel oxide and high-nickel ternary cathode materials.However,accurately measuring the Li/Ni mixing degree is difficult due to the preferred orient...Li/Ni mixing negatively influences the discharge capacity of lithium nickel oxide and high-nickel ternary cathode materials.However,accurately measuring the Li/Ni mixing degree is difficult due to the preferred orientation of labbased XRD measurements using Bragg–Brentano geometry.Here,we find that employing spherical harmonics in Rietveld refinement to eliminate the preferred orientation can significantly decrease the measurement error of the Li/Ni mixing ratio.The Li/Ni mixing ratio obtained from Rietveld refinement with spherical harmonics shows a strong correlation with discharge capacity,which means the electrochemical capacity of lithium nickel oxide and high-nickel ternary cathode can be estimated by the Li/Ni mixing degree.Our findings provide a simple and accurate method to estimate the Li/Ni mixing degree,which is valuable to the structural analysis and screening of the synthesis conditions of lithium nickel oxide and high-nickel ternary cathode materials.展开更多
Resistive switching devices with a high self-rectifying ratio are important for achieving the crossbar memristor array that overcomes the sneak current issue.Herein,we demonstrate a single amorphous lithium lanthanum ...Resistive switching devices with a high self-rectifying ratio are important for achieving the crossbar memristor array that overcomes the sneak current issue.Herein,we demonstrate a single amorphous lithium lanthanum titanium oxide(LLTO)layer based Pt/LLTO/Pt device possessing a self-rectifying ratio higher than 1 × 10^(4) that is comparable to the reported devices with complicated multi-layer stacking structures.Moreover,the device shows forming-free and highly uniform bipolar resistive switching(BRS)characteristic that facilitates the potential applications.The trap-controlled and trap-free space charge limited conductions are demonstrated to dominate the high and low resistance states of the device,respectively.The fast migration of lithium ions under external voltage accelerates the electron injection across the Pt/LLTO interface and also the space charge accumulation in the LLTO layer,and as a result,the high performance of the Pt/LLTO/Pt device was achieved.As demonstrated Pt/LLTO/Pt device sheds a light on the potential applications of the lithium ionic conductors in self-rectifying resistive switching devices.展开更多
Crystal of lithium boric oxide(LBO)crystallizes in the orthorhombic system with a=8.446,6=7.380 and c=5.147A in the unit cell.Large transparent crystals were grown in flux on seeding.Only dislocations occur in the hig...Crystal of lithium boric oxide(LBO)crystallizes in the orthorhombic system with a=8.446,6=7.380 and c=5.147A in the unit cell.Large transparent crystals were grown in flux on seeding.Only dislocations occur in the high quality crystal with density ranging from 30 to 100/cm^(2) and they run all in straight.展开更多
As the earliest commercial cathode material for lithium-ion batteries,lithium cobalt oxide(LiCoO_(2)) shows various advantages,including high theoretical capacity,excellent rate capability,compressed electrode density...As the earliest commercial cathode material for lithium-ion batteries,lithium cobalt oxide(LiCoO_(2)) shows various advantages,including high theoretical capacity,excellent rate capability,compressed electrode density,etc.Until now,it still plays an important role in the lithium-ion battery market.Due to these advantages,further increasing the charging cutoff voltage of LiCoO_(2)to guarantee higher energy density is an irresistible development trend of LiCoO_(2)cathode materials in the future.However,using high charging cutoff voltage may induce a lot of negative effects,especially the rapid decay of cycle capacity.These are mainly caused by rapid destruction of crystal structure and aggravation of interface side reaction at high voltage during the cycle.Therefore,how to maintain a stable crystal structure of LiCoO_(2)to ensure the excellent long cycle performance at high voltage is a hot research issue in the further application of LiCoO_(2).In this review,we summarized the failure causes and extensive solutions of LiCoO_(2)at high voltage and promoted some new modification strategies.Moreover,the development trend of solving the failure problem of high-voltage LiCoO_(2)in the future such as defect engineering and high-temperature shock technique is also discussed.展开更多
Several series of LiRE x Mn 2-x O 4(RE=Ce, Nd) samples prepared at different contents and in different rare earth metals substitution were studied in order to further understand the dependence of the elec...Several series of LiRE x Mn 2-x O 4(RE=Ce, Nd) samples prepared at different contents and in different rare earth metals substitution were studied in order to further understand the dependence of the electrochemical performance on the doping rare earth metals. These cathodes were more tolerant to repeat lithium extraction and insertion than a standard LiMn 2O 4 spinel electrode in spite of a small reduction in the initial capacity. X ray photoelectron spectroscopy results show that the Mn 4+ contents for spinel LiMn 2O 4 directly affected the initial capacity and cyclability of LiMn 2O 4.展开更多
Here we demonstrate a theory-driven, novel dual-shell coating system of Li_(2)SrSiO_(4) and Al_(2)O_(3), achieved via a facile and scalable sol-gel technique on LiCoO_(2) electrode particles. The optimal thickness of ...Here we demonstrate a theory-driven, novel dual-shell coating system of Li_(2)SrSiO_(4) and Al_(2)O_(3), achieved via a facile and scalable sol-gel technique on LiCoO_(2) electrode particles. The optimal thickness of each coating can lead to increased specific capacity(~185 m Ah/g at 0.5 C-rate) at a cut-off potential of 4.5 V, and greater cycling stability at very high C rates(up to 10 C) in half-cells with lithium metal. The mechanism of this superior performance was investigated using a combination of X-ray and electron characterization methods. It shows that the results of this investigation can inform future studies to identify still better dual-shell coating schemes, achieved by such industrially feasible techniques, for application on similar, nickel-rich cathode materials.展开更多
Lithium-substituted LixMn2O4 （x = 0.98, 1.03, 1.08） spinel samples were synthesized by solid-state reaction. X-ray diffraction （XRD） patterns show that the prepared samples have a spinel structure with a space gro...Lithium-substituted LixMn2O4 （x = 0.98, 1.03, 1.08） spinel samples were synthesized by solid-state reaction. X-ray diffraction （XRD） patterns show that the prepared samples have a spinel structure with a space group of Fd 3 m. The cubic lattice parameter was determined from least-squares fitting of the XRD data. Li1.03Mn2O4 shows high capacity at both low and high current densities, while Lil.08Mn2O4shows good cycling performance but relatively low capacity when cycled at both room and elevated temperatures. A variety of electrochemical methods were employed to investigate the electrochemical properties of these series of spinel LixMn2O4.展开更多
Nano-LiMn2O4 cathode materials with nano-sized particles are synthesized via a citric acid assisted sol-gel route. The structure, the morphology and the electrochemical properties of the nano-LiMn204 are investigated....Nano-LiMn2O4 cathode materials with nano-sized particles are synthesized via a citric acid assisted sol-gel route. The structure, the morphology and the electrochemical properties of the nano-LiMn204 are investigated. Compared with the micro-sized LiMn2O4, the nano-LiMn2O4 possesses a high initial capacity （120 mAh/g） at a discharge rate of 0.2 C （29.6 mA/g）. The nano-LiMn2O4 also has a good high-rate discharge capability, retaining 91% of its capacity at a discharge rate of 10 C and 73~ at a discharge rate of 40 C. In particular, the nano-LiMn2O4 shows an excellent high-rate pulse discharge capability. The cut-off voltage at the end of 50-ms pulse discharge with a discharge rate of 80 C is above 3.40 V, and the voltage returns to over 4.10 V after the pulse discharge. These results show that the prepared nano-LiMn2O4 could be a potential cathode material for the power sources with the capability to deliver very high-rate pulse currents.展开更多
Spinel LiMn_(2)O_(4)has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost,non-toxicity and easy manufacture.The spinel lithi...Spinel LiMn_(2)O_(4)has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost,non-toxicity and easy manufacture.The spinel lithium manganese mixed oxides were prepared from lithium nitrate,manganese nitrate and citric acid by a sol-gel method and were characterized by thermogravimetric analysis,X-ray diffraction,cyclic voltammetry and constant current charging-discharging technique.The different sintering temperatures for different time have strong influence on the structure,initial discharge capacity and cycling performance of the lithium manganese oxide.It shows that the lithium manganese oxides sintered at 700℃for 10 h have a single spinel structure and better electrochemical properties.The initial discharging capacity can be up to 125.9 mAh·g^(-1),even after six cycles,it still retains 109.1 mAh·g^(-1).展开更多
文摘This work is a simulation model with the LAMMPS calculation code of an electrode based on alkali metal oxides (lithium, sodium and potassium) using the Lennard Jones potential. For a multiplicity of 8*8*8, we studied a gap-free model using molecular dynamics. Physical quantities such as volume and pressure of the Na-O and Li-O systems exhibit similar behaviors around the thermodynamic ensembles NPT and NVE. However, for the Na2O system, at a minimum temperature value, we observe a range of total energy values;in contrast, for the Li2O system, a minimum energy corresponds to a range of temperatures. Finally, for physicochemical properties, we studied the diffusion coefficient and activation energy of lithium and potassium oxides around their melting temperatures. The order of magnitude of the diffusion coefficients is given by the relation Dli-O >DNa-O for the multiplicity 8*8*8, while for the activation energy, the order is well reversed EaNa-O > EaLi-O.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(Nos.RS-2024-00406500 and RS-2024-00458682).
文摘Lithium-ion batteries(LIBs)that reached their end-of-life(EoL)require recycling,rather than disposal,to recirculate valuable metals and protect the environment.This led us to investigate the extraction of metals from the cathodes of EoL lithium-titanate batteries using ethylenediaminetetraacetic acid disodium(EDTA-2Na).In this work,an orthogonal array was used to design experiments and sig-nal-to-noise calculations were used to define the optimal conditions,which were 0.50 mol/L EDTA-2Na,pH=6,75℃,180 min,2%pulp density,and 300 r/min,resulting in 97.96%,94.79%,96.45%,and 98.89%leaching efficiencies for Li,Ni,Co,and Mn,respectively.Stat-istically significant interactions between variables were then identified using Pearson’s correlation at the 95%confidence interval,and the pH and temperature were found to be significant.The extraction efficiency decreased as the pH increased,but increased as the temperat-ure increased.Machine learning fitting using linear regression for multi-output prediction was unsatisfactory,whereas random forest re-gression(RFR)produced satisfactory results.Permutation importance was computed on the fitted RFR to determine feature importance,and confirmed that the pH and temperature were influential variables;however,the time and pulp density were also noted.As the fitted RFR failed to satisfactorily predict leaching efficiencies in additional validation experiments,we recommend increasing the number of ex-periments and using additional fitting models.An additional analysis that included the initial oxidation-reduction potential(optimal 33.3 mV)revealed this to be the most important variable,the effect of which largely overshadows those of all the other variables.Finally,an environmental assessment highlighted the benefits of the chelating extraction;however,the economic assessment indicated room for improvement.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 52074036 and 52404313)the Beijing Institute of Technology Teli Young Fellow Program。
文摘Spinel lithium manganese oxide(LiMn_(2)O_(4), LMO) emerges as a promising cathode material for future stationary energy storage applications due to its high voltage, safety, cost-effectiveness, and electrochemical performance. However,LMO suffers from rapid capacity degradation caused by the Jahn–Teller effect, Mn dissolution and side reactions. The mechanism remains unclear and even contradictory across various studies, impeding the advancement of high-performance LMO and its widespread utilization. In this study, 14 Ah commercial-level LMO batteries were manufactured and assessed.The mechanism of capacity attenuation in cycle-aged cells at room temperature(RT, 25℃) and high temperature(HT,55℃) storage cells was systematically investigated through the application of electrochemical quantitative methods. The results indicate specific capacity losses of approximately 6.26% and 2.55% for the cathodes in RT cycle-aged cells and HT storage cells, respectively, in comparison to fresh cells. These values are lower than the 12.54% and 6.99% capacity losses observed in RT cycle-aged cells and HT storage cells. While RT cycle-aging and HT storage conditions do not lead to irreversible capacity loss on the anode side. The results suggest that the primary causes of irreversible capacity degradation are not located on the cathode or anode. Nevertheless, significant polarization arises from the continuous growth of the solid electrolyte interphase(SEI), believed to be catalyzed by Mn deposited on the anode, which is considered harmful.This study elucidates that inhibiting the dissolution of Mn from the cathode, facilitating its transport in the electrolyte,promoting its deposition on the anode, and catalyzing the decomposition of the electrolyte are crucial factors for enhancing the performance of LMO batteries.
基金Funded by the National Natural Science Foundation of China(Nos.21561016,21661015)Jiangxi Provincial Science&Technology Program(Nos.20133BBE50010,20142BDH80020,and 20161BBE50052)Science&Technology Program of Jiangxi Provincial Education Bureau(No.GJJ150775)
文摘The capacity fade of spinel lithium manganese oxide in lithium-ion batteries is a bottleneck challenge for the large-scale application.The traditional opinion is that Mn（Ⅱ） ions in the anode are reduced to the metallic manganese that helps for catalyzing electrolyte decomposition.This could poison and damage the solid electrolyte interface（SEI） film,leading to the the capacity fade in Li-ion batteries.We propose a new mechanism that Mn（Ⅱ） deposites at the anode hinders and/or blocks the intercalation/de-intercalation of lithium ions,which leads to the capacity fade in Li-ion batteries.Based on the new mechanism assumption,a kind of new structure with core-shell characteristic is designed to inhabit manganese ion dissolution,thus improving electrochemical cycle performance of the cell.By the way,this mechanism hypothesis is also supported by the results of these experiments.The LiMn2-xTixO4 shell layer enhances cathode resistance to corrosion attack and effectively suppresses dissolution of Mn,then improves battery cycle performance with LiMn_2O_4 cathode,even at high rate and elevated temperature.
基金supported by National Research Foundation of Korea grant from the Korean government (MSIP) (NRF2019R1C1C1002249, and NRF-2017M1A2A2044506)。
文摘Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical properties. However, these properties are limited by the rapid fading of cycling retention, particularly at high temperatures, because of the severe Mn corrosion triggered by the chemical reaction with fluoride(F-) species existing in the cell. To alleviate this issue, three types of silyl ether(Si–O)-functionalized task-specific additives are proposed, namely methoxytrimethylsilane, dimethoxydimethylsilane, and trimethoxymethylsilane. Ex-situ NMR analyses demonstrated that the Si-additives selectively scavenged the F-species as Si forms new chemical bonds with F via a nucleophilic substitution reaction due to the high binding affinity of Si with F-, thereby leading to a decrease in the F concentration in the cell. Furthermore, the addition of Si-additives in the electrolyte did not significantly affect the ionic conductivity or electrochemical stability of the electrolyte, indicating that these additives are compatible with conventional electrolytes. In addition, the cells cycled with Si-additives exhibited improved cycling retention at room temperature and 45 °C. Among these candidates, a combination of MTSi and the LMO cathode was found to be the most suitable choice in terms of cycling retention(71.0%), whereas the cell cycled with the standard electrolyte suffered from the fading of cycling retention triggered by Mn dissolution(64.4%). Additional ex-situ analyses of the cycled electrodes using SEM, TEM, EIS, XPS, and ICP-MS demonstrated that the use of Si-additives not only improved the surface stability of the LMO cathode but also that of the graphite anode, as the Si-additives prevent Mn corrosion. This inhibits the formation of cracks on the surface of the LMO cathode, facilitating the formation of a stable solid electrolyte interphase layer on the surface of the graphite anode. Therefore, Si-additives modified by Si–O functional groups can be effectively used to increase the overall electrochemical performance of the LMO cathode material.
基金funded by the National Natural Science Foundation of China(grant no.21761132030,21935009)National Key Research and Development Program of China(grant no.2016YFB0901502,2018YFB0905400)Collaboration project between Ningde City&Xiamen University(2017c002)。
文摘Lithium cobalt oxide(LCO)is the dominating cathode materials for lithium-ion batteries(LIBs)deployed in consumer electronic devices for its superior volumetric energy density and electrochemical performances.The constantly increasing demands of higher energy density urge to develop high-voltage LCO via a variety of strategies.However,the corresponding modification mechanism,especially the influence of the long-and short-range structural transitions at high-voltage on electrochemical performance,is still not well understood and needs further exploration.Based on ss-NMR,in-situ X-ray diffraction,and electrochemical performance results,it is revealed that the H3 to H1-3 phase transition dictates the structural reversibility and stability of LCO,thereby determining the electrochemical performance.The introduction of La and Al ions could postpone the appearance of H1-3 phase and induce various types of local environments to alleviate the volume variation at the atomic level,leading to better reversibility of the H1-3 phase and smaller lattice strain,and significantly improved cycle performance.Such a comprehensive long-range,local,and electronic structure characterization enables an in-depth understanding of the structural evolution of LCO,providing a guiding principle for developing high-voltage LCO for high energy density LIBs.
基金financially supported by the Ministry of Science and Technology of China(No.2012CB933403)the National Natural Science Foundation of China(Nos.51425302 and 51302045)the Beijing Municipal Science and Technology Commission(No.Z121100006812003)
文摘Herein, a facile strategy for the synthesis of sandwich pyrolyzed bacterial cellulose（PBC）/graphene oxide（GO） composite was reported simply by utilizing the large-scale regenerated biomass bacterial cellulose as precursor. The unique and delicate structure where three-dimensional interconnected bacterial cellulose（BC） network embedded in two-dimensional GO skeleton could not only work as an effective barrier to retard polysulfide diffusion during the charge/discharge process to enhance the cyclic stability of the Li–S battery, but also offer a continuous electron transport pathway for the improved rate capability.As a result, by utilizing pure sulfur as cathodes, the Li–S batteries assembled with PBC/GO interlayer can still exhibit a capacity of nearly 600 mAh·g^-1 at 3C and only 0.055% capacity decay per cycle can be observed over 200 cycles. Additionally, the cost-efficient and environmentfriendly raw materials may enable the PBC/GO sandwich interlayer to be an advanced configuration for Li–S batteries.
基金Supported by the Fundamental Research Funds for the Central Universitiesthe National Natural Science Foundation of China(Grant Nos. 11974366, 11675246, 12074341, U1832170, and U1832150)+2 种基金the Key Research Program of Chinese Academy of Sciences(Grant No. QYZDJ-SSW-SLH053)the Computer Network Information Center of the Chinese Academy of Sciencesthe Shanghai Supercomputer Center of China。
文摘Lithium plays an increasingly important role in scientific and industrial processes, and it is extremely important to extract lithium from a high Mg^(2+)/Li^(+) mass ratio brine or to recover lithium from the leachate of spent lithiumion batteries. Conventional wisdom shows that Li^(+) with low valence states has a much weaker adsorption(and absorption energy) with graphene than multivalent ions such as Mg^(2+). Here, we show the selective adsorption of Li^(+) in thermally reduced graphene oxide(rGO) membranes over other metal ions such as Mg^(2+), Co^(2+), Mn^(2+),Ni^(2+), or Fe^(2+). Interestingly, the adsorption strength of Li^(+) reaches up to 5 times the adsorption strength of Mg^(2+),and the mass ratio of a mixed Mg^(2+)/Li^(+) solution at a very high value of 500 : 1 can be effectively reduced to 0.7 : 1 within only six experimental treatment cycles, demonstrating the excellent applicability of the rGO membranes in the Mg^(2+)/Li^(+) separation. A theoretical analysis indicates that this unexpected selectivity is attributed to the competition between cation–π interaction and steric exclusion when hydrated cations enter the confined space of the rGO membranes.
基金financial support from the ARC Discovery Project (No. DP160103244)the Baosteel Australia Joint Research and Development Centre (No. BA110016)
文摘We report a “soft” graphene oxide-polymeric organosulfide nanocomposite with improved pseudocapacitive performance for high-potential（1–2.8 V vs. Li^0/Li~＋）, high-capacity（278 mAh/g） and stable（500 cycles） lithium storage.
基金financially Australian Research Council (DE210101157 and FT190100058)。
文摘Lithium-sulfur(Li-S) batteries are promising for high energy-storage applications but suffer from sluggish conversion reaction kinetics and substantial lithium sulfide(Li_(2)S) oxidation barrier,especially under high sulfur loadings.Here,we report a Li cation-doped tungsten oxide(Li_(x)WO_(x)) electrocatalyst that efficiently accelerates the S■HLi_(2)S interconversion kinetics.The incorporation of Li dopants into WO_(x) cationic vacancies enables bidirectional electrocatalytic activity for both polysulfide reduction and Li_(2)S oxidation,along with enhanced Li^(+) diffusion.In conjunction with theoretical calculations,it is discovered that the improved electrocatalytic activity originates from the Li dopant-induced geometric and electronic structural optimization of the Li_(x)WO_(x),which promotes the anchoring of sulfur species at favourable adsorption sites while facilitating the charge transfer kinetics.Consequently,Li-S cells with the Li_(x)WO_(x) bidirectional electrocatalyst show stable cycling performance and high sulfur utilization under high sulfur loadings.Our approach provides insights into cation engineering as an effective electrocatalyst design strategy for advancing high-performance Li-S batteries.
基金supported by the National Key Research and Development Program of China(2022YFA1504100)the National Natural Science Foundation of China(22125903,51872283,and 22005298)+4 种基金Dalian Innovation Support Plan for High Level Talents(2019RT09)Dalian National Laboratory For Clean Energy(DNL),Chinese Academy of Sciences(CAS),DNL Cooperation Fund,CAS(DNL202016 and DNL202019)Dalian Institute of Chemical Physics(DICP I2020032)Exploratory Research Project of Yanchang Petroleum International Limited and DICP(yc-hw-2022ky-01)the Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy(YLU-DNL Fund 2021002 and 2021009).
文摘Lithium-ion batteries(LIBs)with the“double-high”characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable electronics.However,the lithium ion(Li+)-storage performance of the most commercialized lithium cobalt oxide(LiCoO_(2),LCO)cathodes is still far from satisfactory in terms of high-voltage and fast-charging capabilities for reaching the double-high target.Herein,we systematically summarize and discuss high-voltage and fast-charging LCO cathodes,covering in depth the key fundamental challenges,latest advancements in modification strategies,and future perspectives in this field.Comprehensive and elaborated discussions are first presented on key fundamental challenges related to structural degradation,interfacial instability,the inhomogeneity reactions,and sluggish interfacial kinetics.We provide an instructive summary of deep insights into promising modification strategies and underlying mechanisms,categorized into element doping(Li-site,cobalt-/oxygen-site,and multi-site doping)for improved Li+diffusivity and bulkstructure stability;surface coating(dielectrics,ionic/electronic conductors,and their combination)for surface stability and conductivity;nanosizing;combinations of these strategies;and other strategies(i.e.,optimization of the electrolyte,binder,tortuosity of electrodes,charging protocols,and prelithiation methods).Finally,forward-looking perspectives and promising directions are sketched out and insightfully elucidated,providing constructive suggestions and instructions for designing and realizing high-voltage and fast-charging LCO cathodes for next-generation double-high LIBs.
基金Project supported by the Natural Science Foundation of Beijing(Grant No.Z200013)the Beijing Municipal Science&Technology(Grant No.Z191100004719001)the National Natural Science Foundation of China(Grant Nos.52325207 and 22005333)。
文摘Li/Ni mixing negatively influences the discharge capacity of lithium nickel oxide and high-nickel ternary cathode materials.However,accurately measuring the Li/Ni mixing degree is difficult due to the preferred orientation of labbased XRD measurements using Bragg–Brentano geometry.Here,we find that employing spherical harmonics in Rietveld refinement to eliminate the preferred orientation can significantly decrease the measurement error of the Li/Ni mixing ratio.The Li/Ni mixing ratio obtained from Rietveld refinement with spherical harmonics shows a strong correlation with discharge capacity,which means the electrochemical capacity of lithium nickel oxide and high-nickel ternary cathode can be estimated by the Li/Ni mixing degree.Our findings provide a simple and accurate method to estimate the Li/Ni mixing degree,which is valuable to the structural analysis and screening of the synthesis conditions of lithium nickel oxide and high-nickel ternary cathode materials.
基金supported by the National Key Research and Development Program of China(No.2019YFB2005801)the National Natural Science Foundation of China(Nos.52061135205,51731003,51971024,51971023,51971027,51927802)the Beijing Natural Science Foundation Key Program(No.Z190007)。
文摘Resistive switching devices with a high self-rectifying ratio are important for achieving the crossbar memristor array that overcomes the sneak current issue.Herein,we demonstrate a single amorphous lithium lanthanum titanium oxide(LLTO)layer based Pt/LLTO/Pt device possessing a self-rectifying ratio higher than 1 × 10^(4) that is comparable to the reported devices with complicated multi-layer stacking structures.Moreover,the device shows forming-free and highly uniform bipolar resistive switching(BRS)characteristic that facilitates the potential applications.The trap-controlled and trap-free space charge limited conductions are demonstrated to dominate the high and low resistance states of the device,respectively.The fast migration of lithium ions under external voltage accelerates the electron injection across the Pt/LLTO interface and also the space charge accumulation in the LLTO layer,and as a result,the high performance of the Pt/LLTO/Pt device was achieved.As demonstrated Pt/LLTO/Pt device sheds a light on the potential applications of the lithium ionic conductors in self-rectifying resistive switching devices.
文摘Crystal of lithium boric oxide(LBO)crystallizes in the orthorhombic system with a=8.446,6=7.380 and c=5.147A in the unit cell.Large transparent crystals were grown in flux on seeding.Only dislocations occur in the high quality crystal with density ranging from 30 to 100/cm^(2) and they run all in straight.
基金financially supported by the National Natural Science Foundation of China(Nos.52171219 and 91963113)
文摘As the earliest commercial cathode material for lithium-ion batteries,lithium cobalt oxide(LiCoO_(2)) shows various advantages,including high theoretical capacity,excellent rate capability,compressed electrode density,etc.Until now,it still plays an important role in the lithium-ion battery market.Due to these advantages,further increasing the charging cutoff voltage of LiCoO_(2)to guarantee higher energy density is an irresistible development trend of LiCoO_(2)cathode materials in the future.However,using high charging cutoff voltage may induce a lot of negative effects,especially the rapid decay of cycle capacity.These are mainly caused by rapid destruction of crystal structure and aggravation of interface side reaction at high voltage during the cycle.Therefore,how to maintain a stable crystal structure of LiCoO_(2)to ensure the excellent long cycle performance at high voltage is a hot research issue in the further application of LiCoO_(2).In this review,we summarized the failure causes and extensive solutions of LiCoO_(2)at high voltage and promoted some new modification strategies.Moreover,the development trend of solving the failure problem of high-voltage LiCoO_(2)in the future such as defect engineering and high-temperature shock technique is also discussed.
文摘Several series of LiRE x Mn 2-x O 4(RE=Ce, Nd) samples prepared at different contents and in different rare earth metals substitution were studied in order to further understand the dependence of the electrochemical performance on the doping rare earth metals. These cathodes were more tolerant to repeat lithium extraction and insertion than a standard LiMn 2O 4 spinel electrode in spite of a small reduction in the initial capacity. X ray photoelectron spectroscopy results show that the Mn 4+ contents for spinel LiMn 2O 4 directly affected the initial capacity and cyclability of LiMn 2O 4.
基金supported by the U.S. National Science Foundation (CBET-1949870, CBET-2016192, and DMR-1832803)Part of the research was conducted at the Northwest Nanotechnology Infrastructure, a National Nanotechnology Coordinated Infrastructure (NNCI) site at Oregon State University, which is supported, in part, by the U.S. National Science Foundation (NNCI-1542101 and NCC-2025489), and Oregon State University。
文摘Here we demonstrate a theory-driven, novel dual-shell coating system of Li_(2)SrSiO_(4) and Al_(2)O_(3), achieved via a facile and scalable sol-gel technique on LiCoO_(2) electrode particles. The optimal thickness of each coating can lead to increased specific capacity(~185 m Ah/g at 0.5 C-rate) at a cut-off potential of 4.5 V, and greater cycling stability at very high C rates(up to 10 C) in half-cells with lithium metal. The mechanism of this superior performance was investigated using a combination of X-ray and electron characterization methods. It shows that the results of this investigation can inform future studies to identify still better dual-shell coating schemes, achieved by such industrially feasible techniques, for application on similar, nickel-rich cathode materials.
基金the National Natural Science Foundation of China (No. 50272012).
文摘Lithium-substituted LixMn2O4 （x = 0.98, 1.03, 1.08） spinel samples were synthesized by solid-state reaction. X-ray diffraction （XRD） patterns show that the prepared samples have a spinel structure with a space group of Fd 3 m. The cubic lattice parameter was determined from least-squares fitting of the XRD data. Li1.03Mn2O4 shows high capacity at both low and high current densities, while Lil.08Mn2O4shows good cycling performance but relatively low capacity when cycled at both room and elevated temperatures. A variety of electrochemical methods were employed to investigate the electrochemical properties of these series of spinel LixMn2O4.
基金supported by the National Natural Science Foundation for Postdoctoral Scientists of China (Grant No. 20090451554)
文摘Nano-LiMn2O4 cathode materials with nano-sized particles are synthesized via a citric acid assisted sol-gel route. The structure, the morphology and the electrochemical properties of the nano-LiMn204 are investigated. Compared with the micro-sized LiMn2O4, the nano-LiMn2O4 possesses a high initial capacity （120 mAh/g） at a discharge rate of 0.2 C （29.6 mA/g）. The nano-LiMn2O4 also has a good high-rate discharge capability, retaining 91% of its capacity at a discharge rate of 10 C and 73~ at a discharge rate of 40 C. In particular, the nano-LiMn2O4 shows an excellent high-rate pulse discharge capability. The cut-off voltage at the end of 50-ms pulse discharge with a discharge rate of 80 C is above 3.40 V, and the voltage returns to over 4.10 V after the pulse discharge. These results show that the prepared nano-LiMn2O4 could be a potential cathode material for the power sources with the capability to deliver very high-rate pulse currents.
基金This work was financially supported by the Program of YET and NCET and the Specialized Research Fund for the Doctoral Program of Higher Education of MOE of China(No.20050699011).
文摘Spinel LiMn_(2)O_(4)has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost,non-toxicity and easy manufacture.The spinel lithium manganese mixed oxides were prepared from lithium nitrate,manganese nitrate and citric acid by a sol-gel method and were characterized by thermogravimetric analysis,X-ray diffraction,cyclic voltammetry and constant current charging-discharging technique.The different sintering temperatures for different time have strong influence on the structure,initial discharge capacity and cycling performance of the lithium manganese oxide.It shows that the lithium manganese oxides sintered at 700℃for 10 h have a single spinel structure and better electrochemical properties.The initial discharging capacity can be up to 125.9 mAh·g^(-1),even after six cycles,it still retains 109.1 mAh·g^(-1).
