Polar-rich-group triazine-based covalent organic frameworks modified separators with de-solvation effect enables uniform Li deposition for stable lithium-metal anode

Polar-rich-group triazine-based covalent organic frameworks (COF-TzDha) with de-solvation effects as an interlayer are designed. The Li-Li symmetric cell with COF-TzDha modified separators cycles stably without any dendrites in lithium-metal anode. The uneven deposition and high reactivity of lithium-metal anode (LMA) lead to uncontrollable dendrite growth, low Coulombic efficiency, and safety concerns, hindering their commercialization. Here, a representative polar-rich-group triazine-based covalent organic framework (COF-TzDha) with a desolvation effect is designed as an interlayer for stable, dendrite-free LMA. The abundant triazine rings in COF-TzDha as a donor effectively attract lithium ions, while the one-dimensional nanopore structure facilitates lithium-ion migration. The periodic arrangement of polar groups (–OH) in the backbone interacts with electrolyte components (DOL, DME, TFSI − ) to form a hydrogen bonding network that slows solvent molecules transport. Therefore, COF-TzDha effectively desolvates lithium ions from the solvent sheath, promoting uniform lithium ion flux and Li plating/stripping. Theoretical calculations verify that COF-TzDha with abundant adsorption sites and strong adsorption energy facilitates lithium ion de-solvation. Consequently, the introduction of COF-TzDha obtains a high ion mobility (0.75). The Li|COF@PP|Li symmetric cell cycles stably for over 1200 h at 4 mA cm −2 /4.0 mA h cm −2 . The Li|COF@PP|LiFePO 4 full cell also displays highly stable cycling performance with 600 cycles (75.5% capacity retention, ∼100% Coulombic efficiency) at 1 C. This work verifies an effective strategy for inducing uniform Li deposition and achieving dendrite-free, stable LMA using a polar-rich-group COF interlayer with a desolvation effect.