MOFs derived ZnSe/N-doped carbon nanosheets as multifunctional interlayers for ultralong-Life lithium-sulfur batteries

The shuttle effect and slow conversion rate of lithium polysulfides（LiPSs） have become the main obstructs to the development of lithium-sulfur（Li-S） batteries.Herein,the low cost metal-organic frameworks derived nitrogen-doped carbon nanosheets embedded with zinc selenide nanoparticles（ZnSe/NC nanosheets） were designed and synthesized for Li-S batteries.As the LiPSs trapping-layer,these nanocomposites provide some key benefits:（1） The nitrogen doping changes local electron distribution in the carbon nanosheets,thus the electrical conductivity is greatly improved for facilitating the transport of electrons/ions.（2） Nitrogen atoms and ZnSe nanoparticles play an important role in anchoring the LiPSs via chemical interactions.（3） The remarkable catalytic activity of ZnSe nanoparticles can accelerate the redox kinetics of LiPSs.As a result,the Li-S battery with the ZnSe/NC nanosheets modified separator exhibits ultralong lifespan over 1500 cycles with a small capacity loss of only 0.046% per cycle at 1 C,which is superior over those reported values.Furthermore,the Li-S battery with a high sulfur loading of 4.71 mg cm-2can still maintain a high areal capacity of 4.28 mAh cm-2 after 50 cycles.This work provides a new route to the design of multifunctional low cost and high-performance separators for remarkably stable Li-S batteries.