Developing a One-Pot Strategy to Synthesize Metal–Covalent Organic Frameworks as Catalysts for Polysulfide Conversion and Ion Calibrators for Lithium Deposition

Abstract

Introducing metals into covalent organic frameworks (COFs) to synthesize metal-COFs (MCOFs) presents novel opportunities for designing highly efficient catalysts to address the sluggish conversion of polysulfides and for developing effective ion calibrators to mitigate uncontrolled lithium dendrite growth in lithium–sulfur batteries (LSBs). Herein, a facile one-pot strategy is proposed to integrate Zn single atoms into the COF framework through coordination with N and O atoms. Comprehensive characterizations of the microstructure, morphology, and chemical environment provide convincing evidence that Zn exists in Zn-COF as single atoms with a +2 state. Leveraging the synergistic advantages of a high Zn content (12.43%) and an ordered porous structure, Zn-COF demonstrates excellent catalytic activity for polysulfide conversion, effectively suppressing the shuttle effect and enhancing reaction kinetics. Additionally, the ordered porous structure promotes a uniform lithium-ion flow, facilitating homogeneous lithium deposition. Consequently, the comprehensive electrochemical performance of LSBs is significantly improved under both conventional and high-sulfur-loading conditions. This work presents a simple and scalable strategy for integrating single atoms into COFs, thereby introducing robust catalytic sites and ordered porous structures for LSBs. It offers valuable insights and opportunities for advancing efficient polysulfide catalysis and effective lithium dendrite inhibition strategies.