Distance-Matched Spatially Separated Bimetallic Centers in a Covalent Organic Framework Accelerate Polysulfide Conversion in Lithium-Sulfur Batteries.

Developing catalysts with tailored metal centers targeting long-chain lithium polysulfides (LiPSs, ∼5.4-5.8 Å) is critical for suppressing shuttle effect and accelerating sluggish redox kinetics in lithium-sulfur batteries (LSBs). However, the spatially compact configurations of conventional metal sites often impose constrained binding geometries, thereby weakening metal-sulfur interactions and limiting catalytic activation. Here, we report a covalent organic framework (COF) catalyst featuring spatially separated bimetallic centers (SSBC-COF) with an intersite distance of 5.8 Å, constructed by coordinating metal ions at two adjacent yet distinct chelating sites within COF. The dual-site coordination design increases the density of accessible Cu sites, while the distance-matched bimetallic configuration enables simultaneous interactions with multiple sulfur atoms. As a result, SSBC-COF delivers markedly enhanced polysulfide confinement and conversion. The LSBs employing SSBC-COF achieve a 270% higher discharge capacity and improved cycling stability with a 65% lower capacity-decay rate than that with PP separator. Moreover, an ultrahigh areal capacity of 14.5 mAh cm