Lithium metal(LM)is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential.Nonetheless,side reactions,volume change,and unwanted lithium dendrite growth seriou...Lithium metal(LM)is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential.Nonetheless,side reactions,volume change,and unwanted lithium dendrite growth seriously limit the practical application of LM.Herein,with the aid of a hard template approach,a novel lithiophilic CoF_(2)-carbon hollow sphere(CoF_(2)@C-HS)composite material is successfully prepared via a facile in-situ fluorination and etching strategy.The lithiophilic CoF_(2) acts as nucleation sites to reduce nucleation overpotential as well as induces the spatial Li deposition and the formation of LiFrich solid electrolyte interphase(SEI),and the hollow carbon matrix can enhance the electrical conductivity and offer free space for LM deposition.Theoretical simulations reveal that the synergistic effect of lithiophilic CoF_(2) and hollow carbon matrix homogenizes the electric field distribution and Li~+flux.Benefiting from these advantages,the CoF_(2)@C-HS-modified copper substrate electrode delivers an enhanced Coulombic efficiency(CE)of 93.7%for 280 cycles at 1 mA cm^(-2)and 1 mA h cm^(-2).The symmetrical cell using CoF_(2)@C-HS can stably cycle more than 1800 h with a low voltage hysteresis of 11 mV at a current density of 0.5 MA cm^(-2)and an areal capacity of 0.5 mA h cm^(-2).Moreover,the Li@CoF_(2)@C-HS composite anode enables more than 300 stable cycles at 1 C with a capacity retention of 95%in LiFePO_(4)-based full cell and 110 stable cycles at 1 C in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)-based highvoltage full cell.This work might shed a new light on designing lithiophilic hosts to spatially confine LM deposition,realizing dendrite-free LM anodes and the practical applications of LM batteries.展开更多
Lithium metal batteries(LMBs)with high energy density are impeded by the instability of solid electrolyte interface(SEI)and the uncontrolled growth of lithium(Li)dendrite.To mitigate these challenges,optimizing the SE...Lithium metal batteries(LMBs)with high energy density are impeded by the instability of solid electrolyte interface(SEI)and the uncontrolled growth of lithium(Li)dendrite.To mitigate these challenges,optimizing the SEI structure and Li deposition behavior is the key to stable LMBs.This study novelty proposes a facile synthesis of MgF_(2)/carbon(C)nanocomposite through the mechanochemical reaction between metallic Mg and polytetrafluoroethylene(PTFE)powders,and its modified polypropylene(PP)separator enhances LMB performance.The in-situ formed highly conductive fluorine-doped C species play a crucial role in facilitating ion/electron transport,thereby accelerating electrochemical kinetics and altering Li deposition direction.During cycling,the in-situ reaction between MgF_(2)and Li leads to the formation of LiMg alloy,along with a LiF-rich SEI layer,which reduces the nucleation overpotential and reinforces the interphase strength,leading to homogeneous Li deposition with dendrite-free feature.Benefiting from these merits,the Li metal is densely and uniformly deposited on the MgF_(2)/C@PP separator side rather than on the current collector side.Furthermore,the symmetric cell with MgF_(2)/C@PP exhibits superb Li plating/stripping performance over 2800 h at 1 mA cm^(-2)and 2 mA h cm^(-2).More importantly,the assembled Li@MgF_(2)/C@PPILiFePO4full cell with a low negative/positive ratio of 3.6delivers an impressive cyclability with 82.7%capacity retention over 1400 cycles at 1 C.展开更多
基金supported by the Natural Science Foundation of China (52277218)the Hubei Provincial Natural Science Foundation of China (2024AFA094)+1 种基金the Excellent Discipline Cultivation Project by JHUN (2023XKZ009)supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division under contract number DE-AC05-00OR22725。
文摘Lithium metal(LM)is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential.Nonetheless,side reactions,volume change,and unwanted lithium dendrite growth seriously limit the practical application of LM.Herein,with the aid of a hard template approach,a novel lithiophilic CoF_(2)-carbon hollow sphere(CoF_(2)@C-HS)composite material is successfully prepared via a facile in-situ fluorination and etching strategy.The lithiophilic CoF_(2) acts as nucleation sites to reduce nucleation overpotential as well as induces the spatial Li deposition and the formation of LiFrich solid electrolyte interphase(SEI),and the hollow carbon matrix can enhance the electrical conductivity and offer free space for LM deposition.Theoretical simulations reveal that the synergistic effect of lithiophilic CoF_(2) and hollow carbon matrix homogenizes the electric field distribution and Li~+flux.Benefiting from these advantages,the CoF_(2)@C-HS-modified copper substrate electrode delivers an enhanced Coulombic efficiency(CE)of 93.7%for 280 cycles at 1 mA cm^(-2)and 1 mA h cm^(-2).The symmetrical cell using CoF_(2)@C-HS can stably cycle more than 1800 h with a low voltage hysteresis of 11 mV at a current density of 0.5 MA cm^(-2)and an areal capacity of 0.5 mA h cm^(-2).Moreover,the Li@CoF_(2)@C-HS composite anode enables more than 300 stable cycles at 1 C with a capacity retention of 95%in LiFePO_(4)-based full cell and 110 stable cycles at 1 C in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)-based highvoltage full cell.This work might shed a new light on designing lithiophilic hosts to spatially confine LM deposition,realizing dendrite-free LM anodes and the practical applications of LM batteries.
基金financially supported by the Natural Science Foundation of China(52277218)the Hubei Provincial Natural Science Foundation of China(2024AFA094)+1 种基金the Excellent Discipline Cultivation Project by JHUN(2023XKZ009)the Graduate Student Innovation Fund of JHUN(KYCXJJ202422).
文摘Lithium metal batteries(LMBs)with high energy density are impeded by the instability of solid electrolyte interface(SEI)and the uncontrolled growth of lithium(Li)dendrite.To mitigate these challenges,optimizing the SEI structure and Li deposition behavior is the key to stable LMBs.This study novelty proposes a facile synthesis of MgF_(2)/carbon(C)nanocomposite through the mechanochemical reaction between metallic Mg and polytetrafluoroethylene(PTFE)powders,and its modified polypropylene(PP)separator enhances LMB performance.The in-situ formed highly conductive fluorine-doped C species play a crucial role in facilitating ion/electron transport,thereby accelerating electrochemical kinetics and altering Li deposition direction.During cycling,the in-situ reaction between MgF_(2)and Li leads to the formation of LiMg alloy,along with a LiF-rich SEI layer,which reduces the nucleation overpotential and reinforces the interphase strength,leading to homogeneous Li deposition with dendrite-free feature.Benefiting from these merits,the Li metal is densely and uniformly deposited on the MgF_(2)/C@PP separator side rather than on the current collector side.Furthermore,the symmetric cell with MgF_(2)/C@PP exhibits superb Li plating/stripping performance over 2800 h at 1 mA cm^(-2)and 2 mA h cm^(-2).More importantly,the assembled Li@MgF_(2)/C@PPILiFePO4full cell with a low negative/positive ratio of 3.6delivers an impressive cyclability with 82.7%capacity retention over 1400 cycles at 1 C.
