To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by graphite/Li me...To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by graphite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accumulation of dead Li,which seriously affects the cycle life of batteries and even causes safety problems.Here,by comparing graphite with two types of hard carbon,it was found that hybrid anode formed by hard carbon and lithium metal,possessing more disordered mesoporous structure and lithophilic groups,presents better performance.Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium.With the synergistic effect of this structure and lithophilic functional groups(–COOH),the reversibility of hard carbon/lithium metal hybrid anode is maintained,promoting uniform deposition of lithium metal and alleviating formation of lithium dendrites.The hybrid anode maintains a 99.5%Coulombic efficiency(CE)after 260 cycles at a specific capacity of 500 m Ah/g.This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.展开更多
High-rate anode materials for lithium-ion batteries are desirable for applications that require high power density.We demonstrate the advantageous rate capability of few-layered graphene nanosheets,with widths of 100-...High-rate anode materials for lithium-ion batteries are desirable for applications that require high power density.We demonstrate the advantageous rate capability of few-layered graphene nanosheets,with widths of 100-200 nm,over micro-scale graphene nanosheets.Possible reasons for the better performance of the former include their smaller size and better conductivity than the latter.Combination of SnO_(2)nanoparticles with graphene was used to further improve the gravimetric capacities of the electrode at high charge-discharge rates.Furthermore,the volumetric capacity of the composites was substantially enhanced compared to pristine graphene due to the higher density of the composites.展开更多
Lithium-ion batteries(LIBs)based on olivine LiFePO_(4)(LFP)offer long cycle/calendar life and good safety,making them one of the dominant batteries in energy storage stations and electric vehicles,especially in China....Lithium-ion batteries(LIBs)based on olivine LiFePO_(4)(LFP)offer long cycle/calendar life and good safety,making them one of the dominant batteries in energy storage stations and electric vehicles,especially in China.Yet scientists have a weak understanding of LFP cathode degradation,which restricts the further development of LFP materials and batteries.Here,we critically review reports on LFP cathode degradation with respect to different electric parameters(including C-rates,storage,and long cycling),mechanical stresses,and thermal fields.The detailed chemical and physical aspects of degradation mechanisms at various scales(i.e.,from atomic to devices)and their causes are comprehensively summarized,and discussions of related concerns are provided in each section.We close with a systematic overview of LFP degradation research and mediation strategies,suggesting future directions for developing robust,safe LFP batteries with long cycle life.展开更多
The growth of Li dendrites and the instability of the solid electrolyte in terphase(SEI)layer during plating/stripping has hin dered the practical applicati on of high-energy-density batteries based on a lithium metal...The growth of Li dendrites and the instability of the solid electrolyte in terphase(SEI)layer during plating/stripping has hin dered the practical applicati on of high-energy-density batteries based on a lithium metal anode.Building a stable interfacial layer is effective in preventing lithium corrosiion by the electrolyte and controlling the deposition of lithium metal.Here,we present a robust polydopamine-Cu ion(PDA-Cu^2+)coati ng layer formed by the aggregation of nanoparticles and Cu ions,which can be obtained by a subtle immersion strategy.We demonstrate that the PDA-Cu^2+ protective layer,with a unique structure comprising nanoparticles,can regulate and guide Li metal deposition,and together with Cu ions,forms a lubricating surface to facilitate uniform Li ion diffusion and induce stable SEI layer formation.Li anodes with this PDA-Cu^2+layer modification ultimately achieve higher Coulombic efficiencies,which are consistently stable for over 650 cycles at 0.5 mA·cm^-2 without Li dendrites.The introduced PDA-Cu^2+ coating can adhere to any material of any shape;addition ally,the operation can be realized on a large scale because of its simplicity.These merits provide a promising approach for developing stable and safe lithium metal batteries.展开更多
Lithium(Li)metal anode holds great promise for high-energy-density rechargeable batteries.However,it suffers from the Li dendrites growth and uncontrollable side reactions with electrolyte due to the unstable solid el...Lithium(Li)metal anode holds great promise for high-energy-density rechargeable batteries.However,it suffers from the Li dendrites growth and uncontrollable side reactions with electrolyte due to the unstable solid electrolyte interphase(SEI)layer.Herein,we propose a facile strategy for the in-situ fabricate of organic-inorganic composite artificial SEI layers on Li surfaces,which consist of organic fluorinated siloxane and inorganic LiF-rich phases.The hybrid artificial SEI endows high mechanical strength(13.1 GPa)and Liþtransfer number(0.62).Such robust SEI protective layers can not only guide uniform nucleation and deposition of Li metal by facilitating uniform Li-ion distribution,but also prevent unfavourable side reactions.Accordingly,the protected metallic lithium anode(PMTFPS-Li)anode enables stable Li plating/stripping performance in symmetric cells for more than 300 h at 4 mA$h/cm^(2)under a high areal capacity of 4 mA/cm^(2).Moreover,the PMTFPS-Li/S cells could maintain more than 300 stable cycles at 0.5C and the PMTFPS-Li/LFP cells present excellent cycling performance(400 cycles at 1C)and enhanced rate capability(110.4 mA$h/g at 3 C).This work will inspire the design of artificial SEI on Li anodes for advanced Li metal batteries.展开更多
基金Financial support from the National Natural Science Foundation of China (22075320)。
文摘To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by graphite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accumulation of dead Li,which seriously affects the cycle life of batteries and even causes safety problems.Here,by comparing graphite with two types of hard carbon,it was found that hybrid anode formed by hard carbon and lithium metal,possessing more disordered mesoporous structure and lithophilic groups,presents better performance.Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium.With the synergistic effect of this structure and lithophilic functional groups(–COOH),the reversibility of hard carbon/lithium metal hybrid anode is maintained,promoting uniform deposition of lithium metal and alleviating formation of lithium dendrites.The hybrid anode maintains a 99.5%Coulombic efficiency(CE)after 260 cycles at a specific capacity of 500 m Ah/g.This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.
基金The authors gratefully acknowledge the National Natural Science Foundation of China(Nos.90206048 and 20371004)the Ministry of Science and Technology of China(Grant Nos.2006CB932701 and 2007AA03Z311)for financial support.
文摘High-rate anode materials for lithium-ion batteries are desirable for applications that require high power density.We demonstrate the advantageous rate capability of few-layered graphene nanosheets,with widths of 100-200 nm,over micro-scale graphene nanosheets.Possible reasons for the better performance of the former include their smaller size and better conductivity than the latter.Combination of SnO_(2)nanoparticles with graphene was used to further improve the gravimetric capacities of the electrode at high charge-discharge rates.Furthermore,the volumetric capacity of the composites was substantially enhanced compared to pristine graphene due to the higher density of the composites.
基金National Natural Science Foundation of China(No.21875284(H.Zhang),22075320(H.Zhang),and U21A20170(X.He))the Ministry of Science and Technology of China(No.2019YFE0100200(X.He)and 2019YFA0705703(L.Wang))the Tsinghua University Initiative Scientific Research Program(No.2019THFS0104(L.Wang)).
文摘Lithium-ion batteries(LIBs)based on olivine LiFePO_(4)(LFP)offer long cycle/calendar life and good safety,making them one of the dominant batteries in energy storage stations and electric vehicles,especially in China.Yet scientists have a weak understanding of LFP cathode degradation,which restricts the further development of LFP materials and batteries.Here,we critically review reports on LFP cathode degradation with respect to different electric parameters(including C-rates,storage,and long cycling),mechanical stresses,and thermal fields.The detailed chemical and physical aspects of degradation mechanisms at various scales(i.e.,from atomic to devices)and their causes are comprehensively summarized,and discussions of related concerns are provided in each section.We close with a systematic overview of LFP degradation research and mediation strategies,suggesting future directions for developing robust,safe LFP batteries with long cycle life.
基金This work was financially supported by the National Natural Science Foundation of China(No.21875284).
文摘The growth of Li dendrites and the instability of the solid electrolyte in terphase(SEI)layer during plating/stripping has hin dered the practical applicati on of high-energy-density batteries based on a lithium metal anode.Building a stable interfacial layer is effective in preventing lithium corrosiion by the electrolyte and controlling the deposition of lithium metal.Here,we present a robust polydopamine-Cu ion(PDA-Cu^2+)coati ng layer formed by the aggregation of nanoparticles and Cu ions,which can be obtained by a subtle immersion strategy.We demonstrate that the PDA-Cu^2+ protective layer,with a unique structure comprising nanoparticles,can regulate and guide Li metal deposition,and together with Cu ions,forms a lubricating surface to facilitate uniform Li ion diffusion and induce stable SEI layer formation.Li anodes with this PDA-Cu^2+layer modification ultimately achieve higher Coulombic efficiencies,which are consistently stable for over 650 cycles at 0.5 mA·cm^-2 without Li dendrites.The introduced PDA-Cu^2+ coating can adhere to any material of any shape;addition ally,the operation can be realized on a large scale because of its simplicity.These merits provide a promising approach for developing stable and safe lithium metal batteries.
基金supported by the National Natural Science Foundation of China(No.21935006).
文摘Lithium(Li)metal anode holds great promise for high-energy-density rechargeable batteries.However,it suffers from the Li dendrites growth and uncontrollable side reactions with electrolyte due to the unstable solid electrolyte interphase(SEI)layer.Herein,we propose a facile strategy for the in-situ fabricate of organic-inorganic composite artificial SEI layers on Li surfaces,which consist of organic fluorinated siloxane and inorganic LiF-rich phases.The hybrid artificial SEI endows high mechanical strength(13.1 GPa)and Liþtransfer number(0.62).Such robust SEI protective layers can not only guide uniform nucleation and deposition of Li metal by facilitating uniform Li-ion distribution,but also prevent unfavourable side reactions.Accordingly,the protected metallic lithium anode(PMTFPS-Li)anode enables stable Li plating/stripping performance in symmetric cells for more than 300 h at 4 mA$h/cm^(2)under a high areal capacity of 4 mA/cm^(2).Moreover,the PMTFPS-Li/S cells could maintain more than 300 stable cycles at 0.5C and the PMTFPS-Li/LFP cells present excellent cycling performance(400 cycles at 1C)and enhanced rate capability(110.4 mA$h/g at 3 C).This work will inspire the design of artificial SEI on Li anodes for advanced Li metal batteries.
