The polysulfide shuttling and sluggish redox kinetics, due to the notorious adsorption-catalysis underperformance, are the ultimate obstacles of the practical application of lithium-sulfur (Li-S) batteries. Conventional carbon-based and transition metal compound-based material solutions generally suffer from poor catalysis and adsorption, respectively, despite the performance gain in terms of the other. Herein, we have enhanced polysulfide adsorption-catalytic capability and protected the Li anode using a complementary bimetallic carbide electrocatalyst, Co₃Mo₃C, modified commercial separator. With this demonstration, the potentials of bimetal compounds, which have been well recognized in other environmental catalysis, are also extended to Li-S batteries. Coupled with this modified separator, a simple cathode (S/Super P composite) can deliver high sulfur utilization, high rate performance, and excellent cycle stability with a low capacity decay rate of ∼0.034% per cycle at 1 C up to 1000 cycles. Even at a high S-loading of 8.0 mg cm⁻² with electrolyte/sulfur ratio=6 mL g⁻¹, the cathode still exhibits high areal capacity of ∼6.8 mA h cm⁻². The experimental analysis and the first principles calculations proved that the bimetallic carbide Co₃Mo₃C provides more binding sites for adsorbing polysulfides and catalyzing the multiphase conversion of sulfur/polysulfide/sulfide than monometallic carbide Mo₂C. Moreover, the modified separator can be reutilized with comparable electrochemical performance. We also showed other bimetallic carbides with similar catalytic effects on Li S batteries and this material family has great promise in different energy electrocatalytic systems.

本文報導了一種鈷-鉬雙金屬碳化物(Co₃Mo₃C)催化材料用 於修飾鋰硫電池隔膜, 強化多硫化鋰的化學吸附和催化轉化. 所組 裝的電池表現出優異的電化學性能, 即使在8.0 mg cm⁻² 的硫面積 負載量條件下, 面積比容量仍高達6.8 mA h cm⁻². 理論計算結果表 明, 相比于單一金屬碳化物Mo₂C, 雙金屬碳化物Co₃Mo₃C具有更多的活性位點, 更利於化學固定多硫化鋰, 並催化多硫化鋰間相互轉 化; 同時, Ni₃Mo₃C和Fe₃Mo₃C亦表現出類似的高催化活性. 本研究 對高性能鋰硫電池關鍵催化材料的設計具有一定的指導意義.