The disorganized lithium dendrites and unstable solid electrolyte interphase(SEI)severely impede the practical application of lithium metal batteries(LMBs).Herein,the N-Zn-F coordinated triazine-based covalent organic...The disorganized lithium dendrites and unstable solid electrolyte interphase(SEI)severely impede the practical application of lithium metal batteries(LMBs).Herein,the N-Zn-F coordinated triazine-based covalent organic framework(TTA-COF-ZnF_(2))is fabricated for the first time as an artificial SEI layer on the surface of lithium metal anodes(LMAs)to handle these issues.Zn-N coordination in onedimensional(1D)ordered COF can increase lithiophilic sites,reduce the Li-nucleation barrier,and regulate the Li+local coordination environment by optimizing surface charge density around the Zn metal.The electron-rich state induced by strong electron-withdrawing F-groups constructs electronegative nanochannels,which trigger efficient Li+desolvation.These beneficial attributes boost Li^(+)transfer,and homogenize Li^(+)flux,leading to uniform Li deposition.Besides,the lithiophilic triazine ring polar groups in TTA-COF-ZnF_(2)further facilitate the Li^(+)migration.The latent working mechanism of adjusting Li deposition behaviors and stabilizing LMAs for TTA-COF-ZnF_(2)is illustrated by detailed in-situ/ex-situ characterizations and density functional theory(DFT)calculations.As expected,TTA-COF-ZnF_(2)-modified Li|Cu half cells deliver a higher Coulombic efficiency(CE)of 98.4% over 250 cycles and lower nucleation overpotential(11 mV)at 1 mA cm^(-2),while TTA-COF-ZnF_(2)@Li symmetric cells display a long lifespan over3785 h at 2 mA cm^(-2).The TTA-COF-ZnF_(2)@Li|S full cells exert ultra high capacity retention of 81%(837 mA h g^(-1))after 600 cycles at 1C.Besides,the TTA-COF-ZnF_(2)@Li|LFP full cells with a high loading of 7.1 mg cm^(-2)exert ultrahigh capacity retention of 89%(108 mAh g^(-1))after 700 cycles at 5C.This synergistic strategy in N-Zn-F coordinated triazine-based COF provides a new insight to regulate the uniform platins/stripping behaviors for developing ultra-stable and dendrite-free LMBs.展开更多
基金financially supported by the National Natural Science Foundation of China(52472093,52176185)the Department of Science and Technology of Hubei Province of China(2022CFA069,2022BAA086)。
文摘The disorganized lithium dendrites and unstable solid electrolyte interphase(SEI)severely impede the practical application of lithium metal batteries(LMBs).Herein,the N-Zn-F coordinated triazine-based covalent organic framework(TTA-COF-ZnF_(2))is fabricated for the first time as an artificial SEI layer on the surface of lithium metal anodes(LMAs)to handle these issues.Zn-N coordination in onedimensional(1D)ordered COF can increase lithiophilic sites,reduce the Li-nucleation barrier,and regulate the Li+local coordination environment by optimizing surface charge density around the Zn metal.The electron-rich state induced by strong electron-withdrawing F-groups constructs electronegative nanochannels,which trigger efficient Li+desolvation.These beneficial attributes boost Li^(+)transfer,and homogenize Li^(+)flux,leading to uniform Li deposition.Besides,the lithiophilic triazine ring polar groups in TTA-COF-ZnF_(2)further facilitate the Li^(+)migration.The latent working mechanism of adjusting Li deposition behaviors and stabilizing LMAs for TTA-COF-ZnF_(2)is illustrated by detailed in-situ/ex-situ characterizations and density functional theory(DFT)calculations.As expected,TTA-COF-ZnF_(2)-modified Li|Cu half cells deliver a higher Coulombic efficiency(CE)of 98.4% over 250 cycles and lower nucleation overpotential(11 mV)at 1 mA cm^(-2),while TTA-COF-ZnF_(2)@Li symmetric cells display a long lifespan over3785 h at 2 mA cm^(-2).The TTA-COF-ZnF_(2)@Li|S full cells exert ultra high capacity retention of 81%(837 mA h g^(-1))after 600 cycles at 1C.Besides,the TTA-COF-ZnF_(2)@Li|LFP full cells with a high loading of 7.1 mg cm^(-2)exert ultrahigh capacity retention of 89%(108 mAh g^(-1))after 700 cycles at 5C.This synergistic strategy in N-Zn-F coordinated triazine-based COF provides a new insight to regulate the uniform platins/stripping behaviors for developing ultra-stable and dendrite-free LMBs.
