Polysulfide Immobilization and Sulfur Conversion Kinetics Promotion via a Tetrathiafulvalene-Crown Ether COF@Graphene...

The rational design of conversion-kinetics-promoting framework architectures offers a powerful strategy to overcome the polysulfide shuttling and sluggish conversion kinetics that limit lithium-sulfur (Li-S) batteries. Here, we report a new covalent organic framework, TUS-44, constructed from tetrathiafulvalene-based 4,4',4'',4'''-([2,2'-bi(1,3-dithiolylidene)]-4,4',5,5'-tetrayl)tetraaniline and benzo[18]crown-6-derived 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[b,k][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl) tetrabenzaldehyde linkers. The resulting imine-linked, π-conjugated framework integrates heteroatom-rich coordination sites within an electron-delocalized π-conjugated backbone, establishing a hierarchical, site-specific interaction network (N > O > S) that governs Li⁺ coordination, polysulfide anchoring, and dynamic charge redistribution. When coupled with conductive graphene to form an interfacial TUS-44@G architecture, the hybrid layer functions as a chemisorptive, conversion-kinetics-promoting interface that regulates soluble polysulfides, facilitates interfacial charge-transfer, and stabilizes intermediate species throughout cycling. This synergistic chemical-electronic coupling yields remarkable electrochemical performance: a high reversible capacity of 1455.7 mA h g^-1 at 0.2 A g^-1, excellent rate capability of 773 mA h g^-1 at 10 A g^-1, and outstanding durability with 0.034% capacity fading per cycle over 1000 cycles at 5 A g^-1. A Li-S pouch cell incorporating TUS-44@G further delivers an outstanding initial energy density of ∼674 Wh kg^-1 at 0.05 A g^-1 (sulfur loading 44.558 mg), underscoring the practical potential of architecting conversion-catalytic framework interfaces for high-energy, durable Li-S batteries.