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
γ-LiV2O5/VO2 composites were synthesized through thermal lithiation reaction of mixed valence (+4, +5) vanadium oxides by lithium bromide. The phase evolution, morphology and discharge behavior at 500 ℃ were investi...γ-LiV2O5/VO2 composites were synthesized through thermal lithiation reaction of mixed valence (+4, +5) vanadium oxides by lithium bromide. The phase evolution, morphology and discharge behavior at 500 ℃ were investigated by thermal gravimeter/differential thermal analysis (TG/DTA), X-ray diffraction(XRD), scanning electron microscopy(SEM) and specific surface analysis(BET). The mixed vanadium oxides are obtained from the pyrolytic decomposition of ammonium metavanadate, with V6O13 as main phase. Results show that the lithiation reaction begins at about 258 ℃, with γ-LiV2O5 and VO2(B) as the product. VO2(B) can transit to VO2(R) in the range of 400-500 ℃, following by grain growth and crystalline development with the increase of temperature and roasting time. The ratio of γ-LiV2O5 to VO2 can be modified by the additive content of lithium bromide. A lattice shearing model about the nucleation and growth of LixV2O5 and VO2(B) inside mixed valence (+4, +5) vanadium oxides (e.g. V6O13, V3O7) is speculated, which is relative to oxygen-/vacancy-diffusion and structural evolution inspired by lithium-insertion. The open-circuit voltage of 2.6 V is observed in the single cell of Li-B/LiCl-KCl/(γ-LiV2O5/VO2) at 500 ℃, and the specific capacities of 146 and 167 mA·h/g (cut-off voltage 1.4 V) are measured for the positive material at 100 mA/cm2 and 200 mA/cm2, respectively.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
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 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
Lithium-selenium(Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with ...Lithium-selenium(Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with high Se content, high Se loading, and high density is employed. The main obstacles are the sluggish conversion kinetics of the dense Se cathodes and the continuous deterioration of the Li-metal anodes.Here, by introducing an acetonitrile(AN)-based electrolyte and replacing the Li electrode with a lithiated graphite, we successfully build a hybrid conversion-intercalation system using a high-content(80 wt%),decent-loading(3.0 mg cm^(-2)), and low-porosity(44%) Se cathode. The as-designed lithiated graphite||Se(LG||Se) cell demonstrated a high Se utilization(97.4%), a long cycle life(3000 cycles), and an ultrahigh average Coulombic efficiency(99.98%). The cell also works well under lean-electrolyte(2 l L mg^(-1)) condition and shows outstanding safety performance in the nail-penetrating test. The combination affords the competitive comprehensive performances, including high volumetric and gravimetric energy densities, long cycling life, and superb safety of the LG||Se cell. In addition, with a newly-designed threeelectrode pouch cell, the lithiation of the graphite anodes could be done with an in-situ lithiation process,indicating the high potential of the as-proposed LG||Se cell for the practical applications.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
Despite the promising energy storage capabilities of high-capacity silicon-and tin-based alloys,as well as fast-charging hard carbon anodes for lithium-ion batteries(LIBs),their widespread industrial adoption is limit...Despite the promising energy storage capabilities of high-capacity silicon-and tin-based alloys,as well as fast-charging hard carbon anodes for lithium-ion batteries(LIBs),their widespread industrial adoption is limited by low initial Coulombic efficiency(ICE).This primarily arises from active lithium loss during the first cycle,caused by the solid electrolyte interface(SEI)formation on anode surfaces and other irreversible side reactions[1,2].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
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Project(2003AA05510) supported by the National High-Tech Research and Development Program of China
文摘γ-LiV2O5/VO2 composites were synthesized through thermal lithiation reaction of mixed valence (+4, +5) vanadium oxides by lithium bromide. The phase evolution, morphology and discharge behavior at 500 ℃ were investigated by thermal gravimeter/differential thermal analysis (TG/DTA), X-ray diffraction(XRD), scanning electron microscopy(SEM) and specific surface analysis(BET). The mixed vanadium oxides are obtained from the pyrolytic decomposition of ammonium metavanadate, with V6O13 as main phase. Results show that the lithiation reaction begins at about 258 ℃, with γ-LiV2O5 and VO2(B) as the product. VO2(B) can transit to VO2(R) in the range of 400-500 ℃, following by grain growth and crystalline development with the increase of temperature and roasting time. The ratio of γ-LiV2O5 to VO2 can be modified by the additive content of lithium bromide. A lattice shearing model about the nucleation and growth of LixV2O5 and VO2(B) inside mixed valence (+4, +5) vanadium oxides (e.g. V6O13, V3O7) is speculated, which is relative to oxygen-/vacancy-diffusion and structural evolution inspired by lithium-insertion. The open-circuit voltage of 2.6 V is observed in the single cell of Li-B/LiCl-KCl/(γ-LiV2O5/VO2) at 500 ℃, and the specific capacities of 146 and 167 mA·h/g (cut-off voltage 1.4 V) are measured for the positive material at 100 mA/cm2 and 200 mA/cm2, respectively.
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 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.
基金supported by the National Natural Science Foundation of China under Grant No. 51802225the funding from the State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology (P2020-001)。
文摘Lithium-selenium(Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with high Se content, high Se loading, and high density is employed. The main obstacles are the sluggish conversion kinetics of the dense Se cathodes and the continuous deterioration of the Li-metal anodes.Here, by introducing an acetonitrile(AN)-based electrolyte and replacing the Li electrode with a lithiated graphite, we successfully build a hybrid conversion-intercalation system using a high-content(80 wt%),decent-loading(3.0 mg cm^(-2)), and low-porosity(44%) Se cathode. The as-designed lithiated graphite||Se(LG||Se) cell demonstrated a high Se utilization(97.4%), a long cycle life(3000 cycles), and an ultrahigh average Coulombic efficiency(99.98%). The cell also works well under lean-electrolyte(2 l L mg^(-1)) condition and shows outstanding safety performance in the nail-penetrating test. The combination affords the competitive comprehensive performances, including high volumetric and gravimetric energy densities, long cycling life, and superb safety of the LG||Se cell. In addition, with a newly-designed threeelectrode pouch cell, the lithiation of the graphite anodes could be done with an in-situ lithiation process,indicating the high potential of the as-proposed LG||Se cell for the practical applications.
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supported by the National Key R&D Program of China(2022YFA1504100)the National Natural Science Foundation of China(22125903,22439003,and 22409192)+2 种基金Liaoning Revitalization Talents Program—Leading Talents(XLYC2402032)the Science and Technology Major Project of Liaoning Province(2024JH1/11700012),DICP(DICP I202324,DICP I202471)the State Key Laboratory of Catalysis(2024SKL-A-001).
文摘Despite the promising energy storage capabilities of high-capacity silicon-and tin-based alloys,as well as fast-charging hard carbon anodes for lithium-ion batteries(LIBs),their widespread industrial adoption is limited by low initial Coulombic efficiency(ICE).This primarily arises from active lithium loss during the first cycle,caused by the solid electrolyte interface(SEI)formation on anode surfaces and other irreversible side reactions[1,2].
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.
