Redox-Active Metal-Covalent Organic Frameworks for Dendrite-Free Lithium Metal Batteries.

Lithium (Li) metal has gained attention as an anode material for lithium-metal batteries (LMBs) owing to its low electrochemical potential, high specific capacity, and low density. However, the accumulation of Li dendrites and unstable solid electrolyte interphases, caused by sluggish Li migration and uneven Li deposition, limit practical LMB applications. This study presents the first report on redox-active metal-covalent organic frameworks (MCOFs) with dual-active centers as functional separators for LMBs. These MCOFs facilitate homogeneous Li nucleation and accelerate Li ion transport. The synergistic effects of redox-active diarylamine units and trinuclear copper clusters modulate local electron-cloud density, regulating microenvironment of Li ions and ensuring homogeneous Li nucleation. The MCOF-based separator's well-defined 1D channels in MCOF-based separator enable uniform Li flux, and promote homogeneous Li deposition, resulting in high Li transference number of 0.93 and an ionic conductivity of 2.01 mS cm at room temperature. The Li|Cu cell demonstrates a low Li nucleation barrier of 16 mV, while the Li symmetric cell exhibits stable Li plating/stripping for over 1600 h at 0.5 mA cm. When coupled with LiFePO cathodes, the assembled LMB exhibits stable capacity retention of ≈98%. This work paves the way for dendrite-free Li metal anodes in high-performance LMBs.