Mitigating the shuttle effect of polysulfides and enhancing their conversion efficiency are critical challenges for the practical application of Li-S batteries. Herein, we present a novel MoS2@CoS2 heteroelectrocatalyst synthesized via a hydrothermal method, used to modify the separator for Li-S batteries. This innovative heterostructure combines the exceptional properties of metallic CoS2 and semiconductor MoS2, creating a synergistic effect that significantly improves electrochemical performance. The built-in electric field at the heterointerface promotes rapid charge transport and enhances surface reaction kinetics, effectively addressing polysulfide shuttle and sluggish redox kinetics. The Li-S battery with MoS2@CoS2 separator exhibits an impressive initial capacity of 1480 mAh g−1 at 0.1 C and maintains 811 mAh g−1 at 3 C, with long-term cycling stability showing a minimal decay rate of 0.05 % per cycle at 1 C. Even with high sulfur loading (6 mg cm−2) and a low electrolyte/sulfur ratio, the cell achieves a high reversible capacity of 4.5 mAh cm−2 at 0.2 C. The innovative approach of integrating semimetal-semiconductor heterointerfaces opens new avenues for the development of high-performance Li-S batteries, addressing critical challenges and paving the way for future technological advancements in the field.