Silicon(Si)is a promising anode material for rechargeable batteries due to its high theoretical capacity and abundance,but its practical application is hindered by the continuous growth of porous solid-electrolyte int...Silicon(Si)is a promising anode material for rechargeable batteries due to its high theoretical capacity and abundance,but its practical application is hindered by the continuous growth of porous solid-electrolyte interphase(SEI),leading to capacity fade.Herein,a LiF-Pie structured SEI is proposed,with LiF nanodomains encapsulated in the inner layer of the organic cross-linking silane matrix.A series of advanced techniques such as cryogenic electron microscopy,time-of-flight secondary ion mass spectrometry,and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry have provided detailed insights into the formation mechanism,nanostructure,and chemical composition of the interface.With such SEI,the capacity retention of LiCoO_(2)||Si is significantly improved from 49.6%to 88.9%after 300 cycles at 100 mA g^(-1).These findings provide a desirable interfacial design principle with enhanced(electro)chemical and mechanical stability,which are crucial for sustaining Si anode functionality,thereby significantly advancing the reliability and practical application of Si-based anodes.展开更多
Fast-charging lithium-ion batteries are highly required,especially in reducing the mileage anxiety of the widespread electric vehicles.One of the biggest bottlenecks lies in the sluggish kinetics of the Li^(+)intercal...Fast-charging lithium-ion batteries are highly required,especially in reducing the mileage anxiety of the widespread electric vehicles.One of the biggest bottlenecks lies in the sluggish kinetics of the Li^(+)intercalation into the graphite anode;slow intercalation will lead to lithium metal plating,severe side reactions,and safety concerns.The premise to solve these problems is to fully understand the reaction pathways and rate-determining steps of graphite during fast Li^(+)intercalation.Herein,we compare the Li^(+)diffusion through the graphite particle,interface,and electrode,uncover the structure of the lithiated graphite at high current densities,and correlate them with the reaction kinetics and electrochemical performances.It is found that the rate-determining steps are highly dependent on the particle size,interphase property,and electrode configuration.Insufficient Li^(+)diffusion leads to high polarization,incomplete intercalation,and the coexistence of several staging structures.Interfacial Li^(+)diffusion and electrode transportation are the main rate-determining steps if the particle size is less than 10μm.The former is highly dependent on the electrolyte chemistry and can be enhanced by constructing a fluorinated interphase.Our findings enrich the understanding of the graphite structural evolution during rapid Li^(+)intercalation,decipher the bottleneck for the sluggish reaction kinetics,and provide strategic guidelines to boost the fast-charging performance of graphite anode.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 ever-growing pursuit for high-energy and low-cost rechargeable batteries has driven the ceaseless research on sodium metal batteries(SMBs)with metallic Na anode,a low redox potential of-2.71 V(vs.standard hydrogen...The ever-growing pursuit for high-energy and low-cost rechargeable batteries has driven the ceaseless research on sodium metal batteries(SMBs)with metallic Na anode,a low redox potential of-2.71 V(vs.standard hydrogen electrode),and a high specific capacity of 1166 mAh g-1.However,its hyperreactivity with liquid electrolytes can cause uncontrollable parasitic reactions and raise safety concerns.Therefore,gel polymer electrolytes(GPEs)in SMBs have attracted immense interest owing to their high energy densities and high safety standards[1],[2].展开更多
Sodium metal anodes(SMAs)sufer from extremely low reversibility(<20%)in carbonate based clectrolytes-this piece of knowledge gained from previous studics has ruled out the application of carbonate solvents for sodi...Sodium metal anodes(SMAs)sufer from extremely low reversibility(<20%)in carbonate based clectrolytes-this piece of knowledge gained from previous studics has ruled out the application of carbonate solvents for sodium metal batteries.Here,we overturn this conclusion by incorporating fluoroethylene carbonate(FEC)as cosolvent that renders a Na plating/stripping fficiency of>95%with conventional NaPF。salt at a regular concentration(1.0M).The peculiar role of FEC is firstly.unraveled via its involvement into the solvation structure,where a threshold FEC concentration with a coordination number>1.2 is needed in guaranteeing high Na reversibility over the long-term.Specifially,by incorporating an average number of 1.2 FEC molecules into the primary Na*solvation sheath,lowest unoccupied molecular orbital(LUMO)levels of such Nat-FEC solvates undergo further decrease,with spin electrons residing either on the O=C 0(O)moiety of FEC or sharing between Na*and its C=:O bond,which ensures a prior FEC decomposition in passivating the Na surface against other carbonate molecules.Further,by adopting cryogenic tranmission electron microscopy(cryo-TEM),we found that the Na filaments grow into substantially larger diameter from-400nm to>1 pum with addition of FEC upon the threshold value.A.highly crstalline and much thiner(-40 nm)slid-electrolyte interphase(SED)is consequently observed to uniformly wrap the Na surface,in contrast to the severely corroded Na as retrieved from the blank electrolyte.The potence of FEC is further demonstrated in a series of"corrosive solvents"such as ethy!l acetate(EA)。trimethyl phosphate(TMP),and actonitrile(AN)enabling highly reversible SMAs in the otherwise unusable solvent systems.展开更多
Revealing the underlying correlations between microscopic structures and the fundamental physicochemical properties is essential for designing better functional materials.Cryogenic electron microscopy(cryo-EM)techniqu...Revealing the underlying correlations between microscopic structures and the fundamental physicochemical properties is essential for designing better functional materials.Cryogenic electron microscopy(cryo-EM)techniques have emerged as an essential tool for obtaining high-resolution images of beam-sensitive materials and studying properties at low temperatures for materials science.In this perspective,we compare and present the similarities and differences in cryo-EM workflows for biomolecules and materials,and briefly enumerate several scenarios of cryo-EM applications in materials science.Finally,we point out the current challenges of cryo-EM and potential directions for its future development.This perspective aims to shed light on the application of cryo-EM in materials science and provide useful guidance.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB2502200)the National Natural Science Foundation of China(NSFC nos.52172257 and 22409211)+2 种基金the China Postdoctoral Science Foundation(No.2023M743739)the Postdoctoral Fellowship Program of CPSF(No.GZC20232939)CAS Youth Interdisciplinary Team。
文摘Silicon(Si)is a promising anode material for rechargeable batteries due to its high theoretical capacity and abundance,but its practical application is hindered by the continuous growth of porous solid-electrolyte interphase(SEI),leading to capacity fade.Herein,a LiF-Pie structured SEI is proposed,with LiF nanodomains encapsulated in the inner layer of the organic cross-linking silane matrix.A series of advanced techniques such as cryogenic electron microscopy,time-of-flight secondary ion mass spectrometry,and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry have provided detailed insights into the formation mechanism,nanostructure,and chemical composition of the interface.With such SEI,the capacity retention of LiCoO_(2)||Si is significantly improved from 49.6%to 88.9%after 300 cycles at 100 mA g^(-1).These findings provide a desirable interfacial design principle with enhanced(electro)chemical and mechanical stability,which are crucial for sustaining Si anode functionality,thereby significantly advancing the reliability and practical application of Si-based anodes.
基金supported by the National Natural Science Foundation of China(NSFC No.52172257 and 22005334)the Natural Science Foundation of Beijing(Grant No.Z200013)the National Key Research and Development Program of China(Grant No.2022YFB2502200).
文摘Fast-charging lithium-ion batteries are highly required,especially in reducing the mileage anxiety of the widespread electric vehicles.One of the biggest bottlenecks lies in the sluggish kinetics of the Li^(+)intercalation into the graphite anode;slow intercalation will lead to lithium metal plating,severe side reactions,and safety concerns.The premise to solve these problems is to fully understand the reaction pathways and rate-determining steps of graphite during fast Li^(+)intercalation.Herein,we compare the Li^(+)diffusion through the graphite particle,interface,and electrode,uncover the structure of the lithiated graphite at high current densities,and correlate them with the reaction kinetics and electrochemical performances.It is found that the rate-determining steps are highly dependent on the particle size,interphase property,and electrode configuration.Insufficient Li^(+)diffusion leads to high polarization,incomplete intercalation,and the coexistence of several staging structures.Interfacial Li^(+)diffusion and electrode transportation are the main rate-determining steps if the particle size is less than 10μm.The former is highly dependent on the electrolyte chemistry and can be enhanced by constructing a fluorinated interphase.Our findings enrich the understanding of the graphite structural evolution during rapid Li^(+)intercalation,decipher the bottleneck for the sluggish reaction kinetics,and provide strategic guidelines to boost the fast-charging performance of graphite anode.
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 National Natural Science Foundation of China(51971250 and 52407257)the Natural Science Foundation of Changsha(kq2208265)+2 种基金the Natural Science Foundation of Hunan Province,China(2023J40759)China Postdoctoral Science Foundation(2023M733933)the State Key Laboratory of Powder Metallurgy at Central South University。
文摘The ever-growing pursuit for high-energy and low-cost rechargeable batteries has driven the ceaseless research on sodium metal batteries(SMBs)with metallic Na anode,a low redox potential of-2.71 V(vs.standard hydrogen electrode),and a high specific capacity of 1166 mAh g-1.However,its hyperreactivity with liquid electrolytes can cause uncontrollable parasitic reactions and raise safety concerns.Therefore,gel polymer electrolytes(GPEs)in SMBs have attracted immense interest owing to their high energy densities and high safety standards[1],[2].
基金sponsored by the National Natural Science Foundation of China(NSFC Nos.21975186,51632001,and 22005334)supports from Natural Science Foundation of Beijing(grant No.Z200013).
文摘Sodium metal anodes(SMAs)sufer from extremely low reversibility(<20%)in carbonate based clectrolytes-this piece of knowledge gained from previous studics has ruled out the application of carbonate solvents for sodium metal batteries.Here,we overturn this conclusion by incorporating fluoroethylene carbonate(FEC)as cosolvent that renders a Na plating/stripping fficiency of>95%with conventional NaPF。salt at a regular concentration(1.0M).The peculiar role of FEC is firstly.unraveled via its involvement into the solvation structure,where a threshold FEC concentration with a coordination number>1.2 is needed in guaranteeing high Na reversibility over the long-term.Specifially,by incorporating an average number of 1.2 FEC molecules into the primary Na*solvation sheath,lowest unoccupied molecular orbital(LUMO)levels of such Nat-FEC solvates undergo further decrease,with spin electrons residing either on the O=C 0(O)moiety of FEC or sharing between Na*and its C=:O bond,which ensures a prior FEC decomposition in passivating the Na surface against other carbonate molecules.Further,by adopting cryogenic tranmission electron microscopy(cryo-TEM),we found that the Na filaments grow into substantially larger diameter from-400nm to>1 pum with addition of FEC upon the threshold value.A.highly crstalline and much thiner(-40 nm)slid-electrolyte interphase(SED)is consequently observed to uniformly wrap the Na surface,in contrast to the severely corroded Na as retrieved from the blank electrolyte.The potence of FEC is further demonstrated in a series of"corrosive solvents"such as ethy!l acetate(EA)。trimethyl phosphate(TMP),and actonitrile(AN)enabling highly reversible SMAs in the otherwise unusable solvent systems.
基金supported by the National Key Research and Development Program of China(grant no.2022YFB2502200)the National Natural Science Foundation of China(NSFC,grant nos.52172257 and 22005334)+2 种基金the Natural Science Foundation of Beijing,China(grant no.Z200013),the China Postdoctoral Science Foundation(grant no.2023M743739)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF,grant no.GZC20232939)the Chinese Academy of Sciences Youth Interdisciplinary Team.
文摘Revealing the underlying correlations between microscopic structures and the fundamental physicochemical properties is essential for designing better functional materials.Cryogenic electron microscopy(cryo-EM)techniques have emerged as an essential tool for obtaining high-resolution images of beam-sensitive materials and studying properties at low temperatures for materials science.In this perspective,we compare and present the similarities and differences in cryo-EM workflows for biomolecules and materials,and briefly enumerate several scenarios of cryo-EM applications in materials science.Finally,we point out the current challenges of cryo-EM and potential directions for its future development.This perspective aims to shed light on the application of cryo-EM in materials science and provide useful guidance.
