Self-exfoliated covalent organic framework nano-mesh enabled regular charge distribution for highly stable lithium metal battery
Li metal batteries have won the fame for the enlarged cell potential and higher theoretical specific capacity. Nevertheless, the commercial implementation is still confronted with inevitable Li dendritic growth and depressed Coulombic efficiency. The Li + transfer behavior is the vital factor to ameliorate the durability of solid electrolyte interphase (SEI). Herein, a self-exfoliated TpTG covalent organic framework (COF) was developed to construct an artificial SEI film. The versatile cationic-skeleton of TpTG could spontaneously drive the formation of nano-mesh with thickness of 3∼6 nm, and facilitate uniform dispersibility on the Li metal surface. Moreover, the 7 Li solid-state nuclear magnetic resonance spectra, Fourier-transform infrared spectra, and density functional theory calculations have identified the energetic lithiophilicity and TFSI – repulsion features. The Cl – coordinated TpTG endowed with abundant lithiophilic sites can reconfigure the charge distribution and expedite the uniform Li + migration adjacent to the electrode|electrolyte interface. The uniform Li + flux distribution redounds to reversible lithium stripping/plating and tames the dendrite formation especially at high-rate protocols. The overwhelming evidences of lower polarization, prolonged lifespan, and compact Li deposition, corroborate the practicability of self-exfoliated TpTG to achieve the goal of high-energy-density Li metal batteries.
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