On account of the lower theoretical capacity of the traditional graphite,the development of reliable anode materials with high capacity and energy density for application in lithium-ion batteries(LIBs)is zealously pur...On account of the lower theoretical capacity of the traditional graphite,the development of reliable anode materials with high capacity and energy density for application in lithium-ion batteries(LIBs)is zealously pursued to meet the ever-increasing power demands for portable mobile devices or(hybrid)electronic vehicles.展开更多
Assuming that the lithiation reaction occurs randomly in individual small particles in the vicinity of the reaction front, a simple model of diffusion- induced dislocations was developed. The diffusion-induced disloca...Assuming that the lithiation reaction occurs randomly in individual small particles in the vicinity of the reaction front, a simple model of diffusion- induced dislocations was developed. The diffusion-induced dislocations are con- trolled by the misfit strain created by the diffusion of solute atoms or the phase transformation in the vicinity of the reaction front. The dislocation density is proportional to the total surface area of the ＂lithiated particle＂ and inversely pro- portional to the particle volume. The diffusion-induced dislocations relieve the diffusion-induced stresses.展开更多
Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2...Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2)C_(8)H_(4)O_(4),Na_(2)TP),an organic salt with a theoretical capacity of 255 mAh·g^(-1),is electroactive towards both lithium and sodium.However,its electrochemical energy storage(EES)process has not been directly observed via in situ characterization techniques and the underlying mechanisms are still under debate.Herein,in situ Raman spectroscopy was employed to track the de/lithiation and de/sodiation processes of Na2TP.The appearance and then disappearance of the–COOLi Raman band at 1625 cm^(-1) during the de/lithiation,and the increase and then decrease of the–COONa Raman band at 1615 cm^(-1) during the de/sodiation processes of Na2TP elucidate the one-step with the 2Li+or 2Na+transfer mechanism.We also found that the inferior cycling stability of Na2TP as an anode for sodium-ion batteries(SIBs)than lithium-ion batteries(LIBs)could be due to the larger ion radium of Na+than Li+,which results in larger steric resistance and polarization during EES.The Na2TP,therefore,shows greater changes in spectra during de/sodiation than de/lithiation.We expect that our findings could provide a reference for the rational design of organic compounds for EES.展开更多
Development of stresses in silicon(Si) anodes of lithium-ion batteries is strongly affected by its mechanical properties. Recent experiments reveal that the mechanical behavior of lithiated silicon is viscoplastic, th...Development of stresses in silicon(Si) anodes of lithium-ion batteries is strongly affected by its mechanical properties. Recent experiments reveal that the mechanical behavior of lithiated silicon is viscoplastic, thereby indicating that lithiation-induced mechanical stresses are dependent on the lithiation reaction rate. Experimental evidence also accumulates that the rate of lithiation reaction is conversely affected by the magnitude of mechanical stresses. These experimental observations demonstrate that lithiation reaction and stress generation in silicon anodes are fully coupled. In this work, we formulate a chemo-mechanical model considering the two-way coupling between lithiation reaction and viscoplastic deformation in silicon nanoparticle anodes.Based on the model, the position of the lithiation interface, the interface velocity, and the lithiation-induced stresses can be solved simultaneously via numerical methods. The predicted interface velocity is in line with experimental measurements reported in the literature. We demonstrate that the lithiation-induced stress field depends on the lithiation reaction through two parameters:the migration velocity and the position of the lithiation interface. We identify a stress-mitigation mechanism in viscoplastic silicon anodes: the stress-regulated lithiation reaction at the interface serves as a "brake" to reduce the interface velocity and mitigate the lithiation-induced stresses, protecting the Si nanoparticle anode from being subjected to excessive mechanical stresses.展开更多
Silicon,a leading candidate for electrode material for lithium-ion batteries,has garnered significant attention.During the initial lithiation process,the alloying reaction between silicon and lithium transforms the pr...Silicon,a leading candidate for electrode material for lithium-ion batteries,has garnered significant attention.During the initial lithiation process,the alloying reaction between silicon and lithium transforms the pristine silicon microstructure from crystalline to amorphous,resulting in plastic deformation of the amorphous phase.This study proposes the free volume theory to develop a fully coupled Cahn-Hilliard phase-field model that integrates viscoplastic deformation,free volume evolution,and diffusion.This model investigates the chemophysical phenomenon of self-limiting behavior occurring during the initial lithiation of silicon anodes.Unlike most existing models,the proposed model considers free volume-dependent diffusion using a physically-based approach.The model’s temporal variation in the lithiated phase thickness aligns well with experimental results,confirming the model’s accuracy.Stress field calculations reveal the coexistence of compressive and tensile stresses within the lithiated phase,which may not cause the limiting effect under the frame of the stress-induced diffusion.Analyses indicate that high effective stress increases free volume,enhancing lithium diffusion and augmenting the diffusion coefficient.Reducing the diffusion coefficient in the lithiated phase due to free volume evolution is the primary cause of self-limiting lithiation.展开更多
Composite Si@SiO_(x)/C anodes with high specific capacity are considered the most promising alternatives to graphite in industrial lithium-ion batteries.However,their cycling stability remains a limiting factor,which ...Composite Si@SiO_(x)/C anodes with high specific capacity are considered the most promising alternatives to graphite in industrial lithium-ion batteries.However,their cycling stability remains a limiting factor,which originates from the severe volume deformation of silicon-derived species.In this work,the cyclabilities of composite anodes are improved by unshackling the highly reversible lithium storage capabilities from the redundancy capacity of the anode materials.A selective LiF-induced lithiation strategy is proposed based on exploiting interface separation energy differences between LiF and the active materials.An interesting preferential redeposition of LiF is observed at the Si@SiO_(x) particles,which differentiates the otherwise similar lithiation potentials of LiC_(x) and Li_(15)Si_(4),thereby enabling lithium storage in graphite that was previously underused.The resulting full cell exhibits better rate and cycling performances without sacrificing specific capacity.In an ultra-high area capacity full cell(4.9 mA h cm^(-2)),the capacity retention increases markedly from 66.1% to 94.2% after 300 cycles.The selective lithiation strategy developed herein is feasible for practical industrial applications,and importantly,it requires no changes to the existing mature lithium-ion battery manufacturing process.This study offers a new approach for the development of silicon/graphite composite anodes with long cycling lifetimes.展开更多
Utilizing MXene to form the multifunctional derivative is a route to construct high-performance electrode materials.To address this issue,V_(2)CT_(x) MXene was employed to realize a derivative of VOx/V_(2)CT_(x) MXene...Utilizing MXene to form the multifunctional derivative is a route to construct high-performance electrode materials.To address this issue,V_(2)CT_(x) MXene was employed to realize a derivative of VOx/V_(2)CT_(x) MXene via a partial oxidation process.Relying on the annealing in the air atmosphere,the controlled oxidation behavior transformed V_(2)CT_(x) MXene partially to V_(2)O_(5) and formed a derivative hybrid of V_(2)O_(5)/V_(2)CT_(x) MXene.As a result,a package of capacity,rate performance,and cyclability can be enhanced.This work explores the derived behavior of MXenes and provides a route for constructing the hybrid with less interface contact.Furthermore,these findings can be extended to other MXene materials.展开更多
High-voltage LiCoO_(2) (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li-ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applic...High-voltage LiCoO_(2) (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li-ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high-voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li-PVDF) coating under air atmosphere. Benefitting from the good film-forming and strong adhesion ability of Li-PVDF, the thus-obtained LiF layer is uniform, dense, and conformal;therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high-voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF-modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g^(−1) at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high-voltage LCO cathodes reported so far.展开更多
Melt-spun Al75-xSi25Crx （x=2, 4, 7, 10, mole fraction, %） alloys were investigated as anode materials for lithium-ion batteries. The as-quenched ribbons consist of nano-grains and metallic glass. The electrochemical...Melt-spun Al75-xSi25Crx （x=2, 4, 7, 10, mole fraction, %） alloys were investigated as anode materials for lithium-ion batteries. The as-quenched ribbons consist of nano-grains and metallic glass. The electrochemical measurements reveal that an activation behavior is exhibited in the anodes. The specific capacity of the A173Si25Cr2 anodes can reach a maximum of 1119 mA.h/g and maintain at 586 mA·hg after 30 cycles. A more stable cycle performance is shown and a capacity loss is only 24% over 30 cycles for Al71Si25Cr4. The intermetallic compounds with Li cannot be detected in the lithiated anodes. After the ribbons were annealed, the specific capacities become much lower due to the formation of inert Al13SiaCr4, and an A1Li phase can be tested in the lithiated anodes. The Cr dissolved in the non-equilibrium alloys causes low lithiation activity and strong structure stability, which could be the main reason of the activation and a restriction of structure evolution.展开更多
Lithium-ion batteries(LIBs)have been used to power various electric devices and store energy,but their toxic components by using inorganic materials generally cause serious environmental issues when disused.Recently,e...Lithium-ion batteries(LIBs)have been used to power various electric devices and store energy,but their toxic components by using inorganic materials generally cause serious environmental issues when disused.Recently,environmentally friendly and naturally abundant organic compounds have been adopted as promising electrode materials for next-generation LIBs.Herein,a new organic anode electrode based on sodium citrate is proposed,which shows gradually activated electrochemical behavior and delivers a high reversible capacity of 776.8 mAh·g^(-1)after 1770 cycles at a current density of 2 A·g^(-1).With the aid of the electrochemical characterization,Fourier-transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analysis,the lithium uptake mechanism of sodium citrate-based anodes is identified to be a combination of three-electron lithiation/delithiation and fast Li+intercalation/deintercalation processes,in which Faradaic reactions could offer a theoretical contribution of312 mAh·g^(-1)and intercalation pseudocapacitance would provide extra capacity.This work demonstrates the great potential for developing high-capacity organic electrodes for LIBs in future.展开更多
Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A （2） and B （3）, isolated from an extract of the stems of Bretschneidera sinensis, is reported. We employed the cyclization reacti...Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A （2） and B （3）, isolated from an extract of the stems of Bretschneidera sinensis, is reported. We employed the cyclization reaction of benzamide by directed lithiation and sequential treatment with sulfur and phosgene as key steps. All new compounds have been fully characterized by means of IR, ^1H NMR, ^13C NMR, and HRMS.展开更多
Rechargeable lithium metal batteries(LMBs)have gained much attention recently.However,the short lifespan and safety issues restrict their commercial applications.Here we report a novel gel polymer electrolyte(GPE)base...Rechargeable lithium metal batteries(LMBs)have gained much attention recently.However,the short lifespan and safety issues restrict their commercial applications.Here we report a novel gel polymer electrolyte(GPE)based on lithiated poly(vinyl chloride-r-acrylic acid)(PVCAALi)to realize dendritesuppressing and long-term stable lithium metal cycling.PVC chains ensure the quick gelation process and high electrolyte uptake,and lithiated PAA segments enable the increase of mechanical strength,acceleration of lithium-ion transmission and improvement of interfacial compatibility.PVCAALi GPE showed much higher mechanical strength compared with other free-standing GPEs in previous works.It displays a superior ionic conductivity of 1.50 m S cm^(-1) and a high lithium-ion transference number of 0.59 at room temperature.Besides,the lithiated GPE exhibits excellent interfacial compatibility with lithium metal anodes.Lithium symmetrical cells with PVCAALi GPE yield low hysteresis of 50 m V over1000 h at 1.0 m A cm^(-2).And the possible mechanism of the lithiated GPE with improved lithium-ion transfer and interfacial property was discussed.Accordingly,both the Li4Ti5O12/Li and lithium-sulfur(Li-S)cells assembled with PVCAALi GPE show outstanding electrochemical performance,retaining high discharge capacities of 133.8 m Ah g^(-1) and 603.8 m Ah g^(-1) over 200 cycles,respectively.This work proves excellent application potential of the highly effective and low-cost PVCAALi GPE in safe and long-life LMBs.展开更多
The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory. It is found that thinfilm electrodes on rigid substrates experie...The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory. It is found that thinfilm electrodes on rigid substrates experience much slower diffusion rates compared with free-standing films with the same material properties and geometric dimensions. More importantly, the study reveals that mechanical driving forces tend to retard diffusion in highly-constrained thin films when lithiation-induced softening is considered, in contrast to the fact that mechanical driving forces always enhance diffusion when deformation is fully elastic. The results provide further proof that nano-particles are a better design option for nextgeneration alloy-based electrodes compared with thin films.展开更多
The structural, electronic, and adsorption properties of Li/Na ions on graphene decorated by epoxy groups are investigated by first-principles calculations based on density functional theory.Our results show that the ...The structural, electronic, and adsorption properties of Li/Na ions on graphene decorated by epoxy groups are investigated by first-principles calculations based on density functional theory.Our results show that the concentration of epoxy groups remarkably affects the structural and electronic properties of graphene.The bandgaps change monotonically from0.16 eV to 3.35 eV when the O coverage increases from 12.5% to 50%(O/C ratio).Furthermore, the highest lithiation potential of 2.714 V is obtained for the case of graphene oxide(GO) with 37.5 % O coverage, while the highest sodiation potential is 1.503 V for GO with 12.5% O coverage.This clearly demonstrates that the concentration of epoxy groups has different effects on Li and Na storage in GO.Our results provide a new insight into enhancing the Li and Na storage by tuning the concentration of epoxy groups on GO.展开更多
SnSb has attracted a great attention in recent investigations as an anode material for Li ion batteries. The formation energies and electronic properties of the Li intercalations in SnSb have been calculated within th...SnSb has attracted a great attention in recent investigations as an anode material for Li ion batteries. The formation energies and electronic properties of the Li intercalations in SnSb have been calculated within the framework of local density functional theory and the first-principles pseudopotential technique. The changes of volumes, band structures, charge density analysis and the electronic density of states for the Li intercalations are presented. The results show that the average Li intercalation formation energy per Li atom is around 2.7 eV.展开更多
The raw carbon nanotubes (CNTs) prepared by chemical vapor deposition (CVD) were used in electrochemical lithiation. To remove the impurity the mild oxidation was done on the samples. The electrochemical characteristi...The raw carbon nanotubes (CNTs) prepared by chemical vapor deposition (CVD) were used in electrochemical lithiation. To remove the impurity the mild oxidation was done on the samples. The electrochemical characteristics of the two samples are investigated by the galvanostatic charge-discharge measurements and cyclic voltammetry. The structural and interfacial changes of the CNTs electrode were analyzed by XRD and FT-IR. The samples show a reversibility of lithium intercalation and de-intercalation. The reversible capacities of the first five cycles are larger than 300 mAh/g and the irreversible capacity of the first cycle was much larger than that mentioned in literatures. There is no identical change in the structure during the charge and discharge. The reactions at the interface between electrode and the electrolyte are similar to those of other carbonaceous materials.展开更多
Recycling millions of metric tons of spent LiFePO_(4) batteries would benefit human health while reducing resource depletion and environmental pollution.However,recovering individual elements from the spent batteries ...Recycling millions of metric tons of spent LiFePO_(4) batteries would benefit human health while reducing resource depletion and environmental pollution.However,recovering individual elements from the spent batteries without generating waste is challenging.Here,we present a distinctive approach for recycling spent LiFePO_(4) batteries at room temperature,where water is the only leaching agent consumed.FePO_(4) and lithium intercalated graphite act as a precursor material for selectively extracting lithium,iron,and phosphorus through charging the LiFePO_(4) batteries to the delithiated state.NaOH solution extracted Fe from FePO_(4) within 30 min and regenerated without consumption,similar to a catalyst.Under the optimal leaching conditions(1 mol·L^(-1) NaOH,0.5 h,NaOH/Fe molar ratio of 4.5),Fe and P leaching efficiencies achieved 89.1%and 99.2%,respectively.The methodology reflected in this research reduced the material cost per kg cathode material to a fraction of previously published reports,only occupies 6.13%of previous reports.In addition,the method improved the battery recycling revenue calculated by the EverBatt model by 2.31 times and 1.94 times over pyrometallurgical and hydrometallurgical methods.The proposed method allows for the convenient recovery of the elemental components of spent LiFePO_(4) batteries.展开更多
Single-ion conducting solid polymer electrolytes are expected to play a vital role in the realization of solid-state Li metal batteries.In this work,a lithiated Nafion(Li-Nafion)-garnet ceramic Li6.25La3 Zr2 Al0.25O12...Single-ion conducting solid polymer electrolytes are expected to play a vital role in the realization of solid-state Li metal batteries.In this work,a lithiated Nafion(Li-Nafion)-garnet ceramic Li6.25La3 Zr2 Al0.25O12(LLZAO)composite solid electrolyte(CSE)membrane with 30μm thickness was prepared for the first time.By employing X-ray photoelectron spectroscopy and transmission electron microscope,the interaction between LLZAO and Li-Nafion was investigated.It is found that the LLZAO interacts with the Li-Nafion to form a space charge layer at the interface between LLZAO and Li-Nafion.The space charge layer reduces the migration barrier of Li-ions and improves the ionic conductivity of the CSE membrane.The CSE membrane containing 10 wt%LLZAO exhibits the highest ionic conductivity of2.26×10-4 S cm-1 at 30℃among the pristine Li-Nafion membrane,the membrane containing 5 wt%,20 wt%,and 30 wt%LLZAO,respectively.It also exhibits a high Li-ion transference number of 0.92,and a broader electrochemical window of 0-+4.8 V vs.Li+/Li than that of 0-+4.0 V vs.Li+/Li for the pristine Li-Nafion membrane.It is observed that the CSE membrane not only inhibits the growth of Li dendrites but also keeps excellent electrochemical stability with the Li electrode.Benefitting from the above merits,the solid-state LiFePO4/Li cell fabricated with the CSE membrane was practically charged and discharged at 30℃.The cell exhibits an initial reversible discharge specific capacity of 160 mAh g-1 with 97%capacity retention after 100 cycles at 0.2 C,and maintains discharge specific capacity of 126 mAh g-1 after500 cycles at 1 C.The CSE membrane prepared with Li-Nafion and LLZAO is proved to be a promising solid electrolyte for advanced solid-state Li metal batteries.展开更多
Intercalation provides to the host materials a means for controlled variation of many physical/chemical properties and dominates the reactions in metal‐ion batteries.Of particular interest is the graphite intercalati...Intercalation provides to the host materials a means for controlled variation of many physical/chemical properties and dominates the reactions in metal‐ion batteries.Of particular interest is the graphite intercalation compounds with intriguing staging structures,which however are still unclear,especially in their nanostructure and dynamic transition mechanism.Herein,the nature of the staging structure and evolution of the lithium(Li)‐intercalated graphite was revealed by cryogenic‐transmission electron microscopy and other methods at the nanoscale.The intercalated Li‐ions distribute unevenly,generating local stress and dislocations in the graphitic structure.Each staging compound is found macroscopically ordered but microscopically inhomogeneous,exhibiting a localized‐domains structural model.Our findings uncover the correlation between the long‐range ordered structure and short‐range domains,refresh the insights on the staging structure and transition of Li‐intercalated/deintercalated graphite,and provide effective ways to enhance the reaction kinetic in rechargeable batteries by defect engineering.展开更多
The lithiated covalent organic framework(named TpPa-SO_(3) Li),which was prepared by a mild chemical lithiation strategy,was introduced in poly(ethylene oxide)(PEO)to produce the composite polymer electrolytes(CPEs).L...The lithiated covalent organic framework(named TpPa-SO_(3) Li),which was prepared by a mild chemical lithiation strategy,was introduced in poly(ethylene oxide)(PEO)to produce the composite polymer electrolytes(CPEs).Li-ion can transfer along the PEO chain or across the layer of TpPa-SO_(3) Li within the nanochannels,resulting in a high Li-ion conductivity of3.01×10^(-4)S/cm at 60℃.When the CPE with 0.75 wt.%TpPa-SO_(3) Li was used in the LiFePO_(4)‖Li solid-state battery,the cell delivered a stable capacity of 125 mA·h/g after 250 cycles at 0.5 C,60℃.In comparison,the cell using the CPE without TpPa-SO_(3) Li exhibited a capacity of only 118 mA·h/g.展开更多
基金This work is supported by the Creative Research Groups of the National Natural Science Foundation of China(Grant No.21521092).
文摘On account of the lower theoretical capacity of the traditional graphite,the development of reliable anode materials with high capacity and energy density for application in lithium-ion batteries(LIBs)is zealously pursued to meet the ever-increasing power demands for portable mobile devices or(hybrid)electronic vehicles.
文摘Assuming that the lithiation reaction occurs randomly in individual small particles in the vicinity of the reaction front, a simple model of diffusion- induced dislocations was developed. The diffusion-induced dislocations are con- trolled by the misfit strain created by the diffusion of solute atoms or the phase transformation in the vicinity of the reaction front. The dislocation density is proportional to the total surface area of the ＂lithiated particle＂ and inversely pro- portional to the particle volume. The diffusion-induced dislocations relieve the diffusion-induced stresses.
基金supported by the National Natural Science Foundation of China(Nos.22005130,22272069,22004054,and 21925404)the Natural Science Foundation of Fujian Province of China(Nos.2021J01988 and 2020J05163).
文摘Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2)C_(8)H_(4)O_(4),Na_(2)TP),an organic salt with a theoretical capacity of 255 mAh·g^(-1),is electroactive towards both lithium and sodium.However,its electrochemical energy storage(EES)process has not been directly observed via in situ characterization techniques and the underlying mechanisms are still under debate.Herein,in situ Raman spectroscopy was employed to track the de/lithiation and de/sodiation processes of Na2TP.The appearance and then disappearance of the–COOLi Raman band at 1625 cm^(-1) during the de/lithiation,and the increase and then decrease of the–COONa Raman band at 1615 cm^(-1) during the de/sodiation processes of Na2TP elucidate the one-step with the 2Li+or 2Na+transfer mechanism.We also found that the inferior cycling stability of Na2TP as an anode for sodium-ion batteries(SIBs)than lithium-ion batteries(LIBs)could be due to the larger ion radium of Na+than Li+,which results in larger steric resistance and polarization during EES.The Na2TP,therefore,shows greater changes in spectra during de/sodiation than de/lithiation.We expect that our findings could provide a reference for the rational design of organic compounds for EES.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11802269, 11525210 & 11621062)the Fundamental Research Funds for the Central Universitiesthe financial support from the One-Hundred Talents Program of Zhejiang University
文摘Development of stresses in silicon(Si) anodes of lithium-ion batteries is strongly affected by its mechanical properties. Recent experiments reveal that the mechanical behavior of lithiated silicon is viscoplastic, thereby indicating that lithiation-induced mechanical stresses are dependent on the lithiation reaction rate. Experimental evidence also accumulates that the rate of lithiation reaction is conversely affected by the magnitude of mechanical stresses. These experimental observations demonstrate that lithiation reaction and stress generation in silicon anodes are fully coupled. In this work, we formulate a chemo-mechanical model considering the two-way coupling between lithiation reaction and viscoplastic deformation in silicon nanoparticle anodes.Based on the model, the position of the lithiation interface, the interface velocity, and the lithiation-induced stresses can be solved simultaneously via numerical methods. The predicted interface velocity is in line with experimental measurements reported in the literature. We demonstrate that the lithiation-induced stress field depends on the lithiation reaction through two parameters:the migration velocity and the position of the lithiation interface. We identify a stress-mitigation mechanism in viscoplastic silicon anodes: the stress-regulated lithiation reaction at the interface serves as a "brake" to reduce the interface velocity and mitigate the lithiation-induced stresses, protecting the Si nanoparticle anode from being subjected to excessive mechanical stresses.
基金the National Natural Science Foundation of China under grant No.12372173the Natural Science Foundation of Shanghai under grant No.23ZR1468600.
文摘Silicon,a leading candidate for electrode material for lithium-ion batteries,has garnered significant attention.During the initial lithiation process,the alloying reaction between silicon and lithium transforms the pristine silicon microstructure from crystalline to amorphous,resulting in plastic deformation of the amorphous phase.This study proposes the free volume theory to develop a fully coupled Cahn-Hilliard phase-field model that integrates viscoplastic deformation,free volume evolution,and diffusion.This model investigates the chemophysical phenomenon of self-limiting behavior occurring during the initial lithiation of silicon anodes.Unlike most existing models,the proposed model considers free volume-dependent diffusion using a physically-based approach.The model’s temporal variation in the lithiated phase thickness aligns well with experimental results,confirming the model’s accuracy.Stress field calculations reveal the coexistence of compressive and tensile stresses within the lithiated phase,which may not cause the limiting effect under the frame of the stress-induced diffusion.Analyses indicate that high effective stress increases free volume,enhancing lithium diffusion and augmenting the diffusion coefficient.Reducing the diffusion coefficient in the lithiated phase due to free volume evolution is the primary cause of self-limiting lithiation.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2020B090919005)the National Key R&D Program of China(2017YFE0127600)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA22010600)Taishan Scholars Program for Young Expert of Shandong Province(tsqn 202103145)the National Natural Science Foundation of China(22179135)the Finance Science and Technology Project of Hainan province(ZDKJ202014)。
文摘Composite Si@SiO_(x)/C anodes with high specific capacity are considered the most promising alternatives to graphite in industrial lithium-ion batteries.However,their cycling stability remains a limiting factor,which originates from the severe volume deformation of silicon-derived species.In this work,the cyclabilities of composite anodes are improved by unshackling the highly reversible lithium storage capabilities from the redundancy capacity of the anode materials.A selective LiF-induced lithiation strategy is proposed based on exploiting interface separation energy differences between LiF and the active materials.An interesting preferential redeposition of LiF is observed at the Si@SiO_(x) particles,which differentiates the otherwise similar lithiation potentials of LiC_(x) and Li_(15)Si_(4),thereby enabling lithium storage in graphite that was previously underused.The resulting full cell exhibits better rate and cycling performances without sacrificing specific capacity.In an ultra-high area capacity full cell(4.9 mA h cm^(-2)),the capacity retention increases markedly from 66.1% to 94.2% after 300 cycles.The selective lithiation strategy developed herein is feasible for practical industrial applications,and importantly,it requires no changes to the existing mature lithium-ion battery manufacturing process.This study offers a new approach for the development of silicon/graphite composite anodes with long cycling lifetimes.
基金support provided by the National Natural Science Foundation of China (grant No.51932005)Liao Ning Revitalization Talents Program (grant No.XLYC1807175)the Research Fund of SYNL,the Science and Technology Research Project of Education Department of jilin Province (grant Nos.JKH20210453KJ,JKH20210449KJ).
文摘Utilizing MXene to form the multifunctional derivative is a route to construct high-performance electrode materials.To address this issue,V_(2)CT_(x) MXene was employed to realize a derivative of VOx/V_(2)CT_(x) MXene via a partial oxidation process.Relying on the annealing in the air atmosphere,the controlled oxidation behavior transformed V_(2)CT_(x) MXene partially to V_(2)O_(5) and formed a derivative hybrid of V_(2)O_(5)/V_(2)CT_(x) MXene.As a result,a package of capacity,rate performance,and cyclability can be enhanced.This work explores the derived behavior of MXenes and provides a route for constructing the hybrid with less interface contact.Furthermore,these findings can be extended to other MXene materials.
基金National Key R&D Program of China(2021YFB3800300).
文摘High-voltage LiCoO_(2) (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li-ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high-voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li-PVDF) coating under air atmosphere. Benefitting from the good film-forming and strong adhesion ability of Li-PVDF, the thus-obtained LiF layer is uniform, dense, and conformal;therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high-voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF-modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g^(−1) at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high-voltage LCO cathodes reported so far.
基金Projects (50871081,51002117,51071117) supported by the National Natural Science Foundation of China
文摘Melt-spun Al75-xSi25Crx （x=2, 4, 7, 10, mole fraction, %） alloys were investigated as anode materials for lithium-ion batteries. The as-quenched ribbons consist of nano-grains and metallic glass. The electrochemical measurements reveal that an activation behavior is exhibited in the anodes. The specific capacity of the A173Si25Cr2 anodes can reach a maximum of 1119 mA.h/g and maintain at 586 mA·hg after 30 cycles. A more stable cycle performance is shown and a capacity loss is only 24% over 30 cycles for Al71Si25Cr4. The intermetallic compounds with Li cannot be detected in the lithiated anodes. After the ribbons were annealed, the specific capacities become much lower due to the formation of inert Al13SiaCr4, and an A1Li phase can be tested in the lithiated anodes. The Cr dissolved in the non-equilibrium alloys causes low lithiation activity and strong structure stability, which could be the main reason of the activation and a restriction of structure evolution.
基金financially supported by the National Natural Science Foundation of China(Nos.21875155,51675275 and 21473119)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJQN201900527)the support from the Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province,Suzhou,China。
文摘Lithium-ion batteries(LIBs)have been used to power various electric devices and store energy,but their toxic components by using inorganic materials generally cause serious environmental issues when disused.Recently,environmentally friendly and naturally abundant organic compounds have been adopted as promising electrode materials for next-generation LIBs.Herein,a new organic anode electrode based on sodium citrate is proposed,which shows gradually activated electrochemical behavior and delivers a high reversible capacity of 776.8 mAh·g^(-1)after 1770 cycles at a current density of 2 A·g^(-1).With the aid of the electrochemical characterization,Fourier-transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analysis,the lithium uptake mechanism of sodium citrate-based anodes is identified to be a combination of three-electron lithiation/delithiation and fast Li+intercalation/deintercalation processes,in which Faradaic reactions could offer a theoretical contribution of312 mAh·g^(-1)and intercalation pseudocapacitance would provide extra capacity.This work demonstrates the great potential for developing high-capacity organic electrodes for LIBs in future.
基金financially supported by the Scientific Research Foundation of Northwest University(No. PR10035)
文摘Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A （2） and B （3）, isolated from an extract of the stems of Bretschneidera sinensis, is reported. We employed the cyclization reaction of benzamide by directed lithiation and sequential treatment with sulfur and phosgene as key steps. All new compounds have been fully characterized by means of IR, ^1H NMR, ^13C NMR, and HRMS.
基金the financial support for this work provided by the National 863 Program of China(Grant number 2012AA03A602)the National Key R&D Program of China(Grant number 2017YFE0114100)+2 种基金the National Natural Science Foundation of China(21805240)the Science and Technology Project of Guangdong Province of China(2019 ST115)the MOE Key Laboratory of Macromolecular Synthesis and Functionalization,Zhejiang University(Grant number 2017MSF05)。
文摘Rechargeable lithium metal batteries(LMBs)have gained much attention recently.However,the short lifespan and safety issues restrict their commercial applications.Here we report a novel gel polymer electrolyte(GPE)based on lithiated poly(vinyl chloride-r-acrylic acid)(PVCAALi)to realize dendritesuppressing and long-term stable lithium metal cycling.PVC chains ensure the quick gelation process and high electrolyte uptake,and lithiated PAA segments enable the increase of mechanical strength,acceleration of lithium-ion transmission and improvement of interfacial compatibility.PVCAALi GPE showed much higher mechanical strength compared with other free-standing GPEs in previous works.It displays a superior ionic conductivity of 1.50 m S cm^(-1) and a high lithium-ion transference number of 0.59 at room temperature.Besides,the lithiated GPE exhibits excellent interfacial compatibility with lithium metal anodes.Lithium symmetrical cells with PVCAALi GPE yield low hysteresis of 50 m V over1000 h at 1.0 m A cm^(-2).And the possible mechanism of the lithiated GPE with improved lithium-ion transfer and interfacial property was discussed.Accordingly,both the Li4Ti5O12/Li and lithium-sulfur(Li-S)cells assembled with PVCAALi GPE show outstanding electrochemical performance,retaining high discharge capacities of 133.8 m Ah g^(-1) and 603.8 m Ah g^(-1) over 200 cycles,respectively.This work proves excellent application potential of the highly effective and low-cost PVCAALi GPE in safe and long-life LMBs.
基金supported by the National Research Foundation of Korea through WCU(R31-2009-000-10083-0)
文摘The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory. It is found that thinfilm electrodes on rigid substrates experience much slower diffusion rates compared with free-standing films with the same material properties and geometric dimensions. More importantly, the study reveals that mechanical driving forces tend to retard diffusion in highly-constrained thin films when lithiation-induced softening is considered, in contrast to the fact that mechanical driving forces always enhance diffusion when deformation is fully elastic. The results provide further proof that nano-particles are a better design option for nextgeneration alloy-based electrodes compared with thin films.
基金Project supported by the National Natural Science Foundation of China(Grant No.11764019)the Education Department of Jiangxi Province,China(Grant No.GJJ170186)Science Foundation for PHDs of Jiangxi Normal University,China(Grant No.7957)
文摘The structural, electronic, and adsorption properties of Li/Na ions on graphene decorated by epoxy groups are investigated by first-principles calculations based on density functional theory.Our results show that the concentration of epoxy groups remarkably affects the structural and electronic properties of graphene.The bandgaps change monotonically from0.16 eV to 3.35 eV when the O coverage increases from 12.5% to 50%(O/C ratio).Furthermore, the highest lithiation potential of 2.714 V is obtained for the case of graphene oxide(GO) with 37.5 % O coverage, while the highest sodiation potential is 1.503 V for GO with 12.5% O coverage.This clearly demonstrates that the concentration of epoxy groups has different effects on Li and Na storage in GO.Our results provide a new insight into enhancing the Li and Na storage by tuning the concentration of epoxy groups on GO.
基金This work was supported by the Natural Science Foundation of Fujian Province under grant No.E032001.
文摘SnSb has attracted a great attention in recent investigations as an anode material for Li ion batteries. The formation energies and electronic properties of the Li intercalations in SnSb have been calculated within the framework of local density functional theory and the first-principles pseudopotential technique. The changes of volumes, band structures, charge density analysis and the electronic density of states for the Li intercalations are presented. The results show that the average Li intercalation formation energy per Li atom is around 2.7 eV.
文摘The raw carbon nanotubes (CNTs) prepared by chemical vapor deposition (CVD) were used in electrochemical lithiation. To remove the impurity the mild oxidation was done on the samples. The electrochemical characteristics of the two samples are investigated by the galvanostatic charge-discharge measurements and cyclic voltammetry. The structural and interfacial changes of the CNTs electrode were analyzed by XRD and FT-IR. The samples show a reversibility of lithium intercalation and de-intercalation. The reversible capacities of the first five cycles are larger than 300 mAh/g and the irreversible capacity of the first cycle was much larger than that mentioned in literatures. There is no identical change in the structure during the charge and discharge. The reactions at the interface between electrode and the electrolyte are similar to those of other carbonaceous materials.
基金the Key-Area Research and Development Program of Guangdong Province(No.2020B090919003)the National Natural Science Foundation of China(No.51872157)+2 种基金Shenzhen Technical Plan Project(Nos.JCYJ20170412170911187 and JCYJ20170817161753629)Guangdong Technical Plan Project(No.2017B090907005)the Key Project of Core Technology Tackling of Guangdong City of Dongguan(No.2019622119003)。
文摘Recycling millions of metric tons of spent LiFePO_(4) batteries would benefit human health while reducing resource depletion and environmental pollution.However,recovering individual elements from the spent batteries without generating waste is challenging.Here,we present a distinctive approach for recycling spent LiFePO_(4) batteries at room temperature,where water is the only leaching agent consumed.FePO_(4) and lithium intercalated graphite act as a precursor material for selectively extracting lithium,iron,and phosphorus through charging the LiFePO_(4) batteries to the delithiated state.NaOH solution extracted Fe from FePO_(4) within 30 min and regenerated without consumption,similar to a catalyst.Under the optimal leaching conditions(1 mol·L^(-1) NaOH,0.5 h,NaOH/Fe molar ratio of 4.5),Fe and P leaching efficiencies achieved 89.1%and 99.2%,respectively.The methodology reflected in this research reduced the material cost per kg cathode material to a fraction of previously published reports,only occupies 6.13%of previous reports.In addition,the method improved the battery recycling revenue calculated by the EverBatt model by 2.31 times and 1.94 times over pyrometallurgical and hydrometallurgical methods.The proposed method allows for the convenient recovery of the elemental components of spent LiFePO_(4) batteries.
基金financially supported by the National Key R&D Program of China(Grant no.2016YFB0100100)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant no.XDA17020404)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(Grant no.XDA09010203)R&D Projects in Key Areas of Guangdong Province(Grant no.2019B090908001)DICP&QIBEBT(Grant no.DICP&QIBEBT UN201702)。
文摘Single-ion conducting solid polymer electrolytes are expected to play a vital role in the realization of solid-state Li metal batteries.In this work,a lithiated Nafion(Li-Nafion)-garnet ceramic Li6.25La3 Zr2 Al0.25O12(LLZAO)composite solid electrolyte(CSE)membrane with 30μm thickness was prepared for the first time.By employing X-ray photoelectron spectroscopy and transmission electron microscope,the interaction between LLZAO and Li-Nafion was investigated.It is found that the LLZAO interacts with the Li-Nafion to form a space charge layer at the interface between LLZAO and Li-Nafion.The space charge layer reduces the migration barrier of Li-ions and improves the ionic conductivity of the CSE membrane.The CSE membrane containing 10 wt%LLZAO exhibits the highest ionic conductivity of2.26×10-4 S cm-1 at 30℃among the pristine Li-Nafion membrane,the membrane containing 5 wt%,20 wt%,and 30 wt%LLZAO,respectively.It also exhibits a high Li-ion transference number of 0.92,and a broader electrochemical window of 0-+4.8 V vs.Li+/Li than that of 0-+4.0 V vs.Li+/Li for the pristine Li-Nafion membrane.It is observed that the CSE membrane not only inhibits the growth of Li dendrites but also keeps excellent electrochemical stability with the Li electrode.Benefitting from the above merits,the solid-state LiFePO4/Li cell fabricated with the CSE membrane was practically charged and discharged at 30℃.The cell exhibits an initial reversible discharge specific capacity of 160 mAh g-1 with 97%capacity retention after 100 cycles at 0.2 C,and maintains discharge specific capacity of 126 mAh g-1 after500 cycles at 1 C.The CSE membrane prepared with Li-Nafion and LLZAO is proved to be a promising solid electrolyte for advanced solid-state Li metal batteries.
基金support from the National Natural Science Foundation of China(NSFC nos.52172257,22005334,21773301 and 52022106)the Natural Science Foundation of Beijing(grant no.Z200013).
文摘Intercalation provides to the host materials a means for controlled variation of many physical/chemical properties and dominates the reactions in metal‐ion batteries.Of particular interest is the graphite intercalation compounds with intriguing staging structures,which however are still unclear,especially in their nanostructure and dynamic transition mechanism.Herein,the nature of the staging structure and evolution of the lithium(Li)‐intercalated graphite was revealed by cryogenic‐transmission electron microscopy and other methods at the nanoscale.The intercalated Li‐ions distribute unevenly,generating local stress and dislocations in the graphitic structure.Each staging compound is found macroscopically ordered but microscopically inhomogeneous,exhibiting a localized‐domains structural model.Our findings uncover the correlation between the long‐range ordered structure and short‐range domains,refresh the insights on the staging structure and transition of Li‐intercalated/deintercalated graphite,and provide effective ways to enhance the reaction kinetic in rechargeable batteries by defect engineering.
基金supported by the State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)the National Natural Science Foundation of China(Nos.21878216,22005215)+1 种基金Hebei Province Innovation Ability Promotion Project(No.20312201D)the National Key Research and Development Program of China(No.2019YFE0118800)。
文摘The lithiated covalent organic framework(named TpPa-SO_(3) Li),which was prepared by a mild chemical lithiation strategy,was introduced in poly(ethylene oxide)(PEO)to produce the composite polymer electrolytes(CPEs).Li-ion can transfer along the PEO chain or across the layer of TpPa-SO_(3) Li within the nanochannels,resulting in a high Li-ion conductivity of3.01×10^(-4)S/cm at 60℃.When the CPE with 0.75 wt.%TpPa-SO_(3) Li was used in the LiFePO_(4)‖Li solid-state battery,the cell delivered a stable capacity of 125 mA·h/g after 250 cycles at 0.5 C,60℃.In comparison,the cell using the CPE without TpPa-SO_(3) Li exhibited a capacity of only 118 mA·h/g.
