Bimetallic Metal–Organic Framework Catalyst to Accelerate Sulfur Conversion Kinetics for High-Performance Lithium–Sulfur Batteries

Lithium-sulfur (Li-S) batteries are highly attractive due to their exceptional theoretical energy density (2600 Wh kg-1) and low cost. However, their practical deployment is limited by critical issues, including pronounced polysulfide shuttling and slow reaction kinetics. In this study, we report the development of a novel Mo-Zn bimetallic ZIF-8 catalyst designed to address these issues. Compared with pristine ZIF-8, the Mo-ZIF-8 catalyst exhibited an effectively tuned surface area and pore structure, significantly enhancing its ability to trap polysulfides. Moreover, the optimized pore architecture increased the exposure of active sites, strengthening the chemical interactions between Mo-ZIF-8 and sulfur species and thereby accelerating sulfur reaction kinetics. The incorporation of Mo also induced a redistribution of the electronic structure around the Zn active sites, boosting the intrinsic conductivity of the catalyst and reducing the electrochemical diffusion resistance during the redox processes. The synergistic design of Mo-Zn active sites further enhanced the chemical adsorption of lithium polysulfides and catalytic conversion of sulfur species. As a result, Li-S batteries with Mo-ZIF-8-modified separators exhibit minimal capacity decay (0.04% per cycle) over 1000 cycles at 1C. Under a high sulfur loading of 5.8 mg cm-2, they achieve an areal capacity of 5.8 mAh cm-2, retaining 5.0 mAh cm-2 after 100 cycles. These findings highlight the potential of bimetallic metal-organic framework (MOF) catalysts in advancing the Li-S battery performance.