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[Display omitted] • CoN-Mo 2 N heterostructure is synthesized by nitriding the CoMoO 4 nanorods; • CoN-Mo 2 N heterostructure has strong adsorption/bidirectional catalytic capacity for polysulfides; • Li-S cells assembled with CoN-Mo 2 N modified separators show excellent electrochemical performance. A single functional material can hardly simultaneously overcome the problems of poor conductivity of active sulfur, shuttle effect and slow redox reaction kinetics of lithium polysulfides (LiPSs) in rechargeable lithium-sulfur batteries. Herein, a multi-functional CoN-Mo 2 N heterostructure nanorods with excellent adsorption capability and bidirectional catalytic ability is introduced. It is found that the CoN-Mo 2 N heterostructure has a significant interaction with LiPSs, and its chemical affinity can promote the adsorption of LiPSs; The Li 2 S nucleation and electrochemical testing results show that the CoN-Mo 2 N heterostructure can promote the uniform nucleation and rapid growth of Li 2 S, where CoN tends to promote the oxidation reaction kinetics, and Mo 2 N promotes the reduction reaction kinetics. The assembled Li-S cells with CoN-Mo 2 N modified separators can deliver outstanding rate performance and long-cycling stability, with a high initial reversible discharge capacity of 1605.8 mAh g−1 at 0.1C, and capacity decay rate per cycle of 0.198 % after 200 cycles at 0.2C. [ABSTRACT FROM AUTHOR]

[Display omitted] • CoSe@NC nanofiber membrane was synthesized by electrospinning and thermal annealing method. • CoSe nanoparticles have strong adsorption and catalytic capability for polysulfides. • Li-S battery with CoSe@NC nanofiber membrane as interlayer shows excellent electrochemical performance. Lithium sulfur (Li-S) batteries have attracted tremendous attention due to their low cost and high theoretical capacity. However, the serious polysulfides shuttle and slow redox reaction kinetics hinder their large-scale commercial applications. Various attempts have been made to solve the problems. Herein, a CoSe@NC nanofiber membrane was prepared by electrospinning method and used as independent functional interlayer for the Li-S batteries. The visualized adsorption experiments show that the CoSe@NC nanofiber exhibits strong adsorption capability for polysulfides; In addition, CoSe nanoparticles with strong catalytic activity can accelerate the conversion of polysulfides. The adsorption-catalysis synergy of CoSe@NC can therefore effectively enhance the rate performance and cycling stability of Li-S batteries. The cell assembled with CoSe@NC functional interlayer delivers a high initial reversible discharge capacity of 1317 mAh g−1 at 0.1 C rate. After 200 cycles at 1.0 C, the capacity decay rate is only 0.16% per cycle. This work provides a feasible way to promote the electrochemical performance of Li-S batteries [ABSTRACT FROM AUTHOR]