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The intrinsic clustering behavior and kinetically sluggish conversion process of lithium polysulfides seriously limit the electrochemical reversibility of sulfur redox reactions in lithium-sulfur (Li-S) batteries. Here, we introduce molybdenum pentachloride (MoCl5) into the electrolyte which could coordinate with lithium polysulfides and inhibit their intrinsic clustering behavior, subsequently serving as an improved mediator with the bi-functional catalytic effect for Li2S deposition and activation. Moreover, the coordination bonding and accelerated conversion reaction can also greatly suppress the dissolution and shuttling of polysulfides. Consequently, such polysulfide complexes enable the Li-S coin cell to exhibit good long-term cycling stability with a capacity decay of 0.078% per cycle after 400 cycles at 2 C, and excellent rate performance with a discharge capacity of 589 mAh/g at 4 C. An area capacity of 3.94 mAh/cm2is also achieved with a high sulfur loading of 4.5 mg/cm2at 0.2 C. Even at -20°C, the modified cell maintains standard discharge plateaus with low overpotential, delivering a high capacity of 741 mAh/g at 0.2 C after 80 cycles. The low-cost and convenient MoCl5additive opens a new avenue for the effective regulation of polysulfides and significant enhancement in sulfur redox conversion.