Porousbowl-shapedVS2nanosheets/graphenecompositeforhigh-ratelithium-ionstorage

Two-dimensional （2D） layered vanadium disulfide （VS2） is a promising anode material for lithium ion batteries （LIBs） due to the high theoretical capacity.However,it remains a challenge to synthesize monodispersed ultrathin VS2 nanosheets to realize the full potential.Herein,a novel solvothermal method has been developed to prepare the monodispersed bowl-shaped NH3-inserted VS2 nanosheets （VS2）.The formation of such a unique structure is caused by the blocked growth of （001） or （002） crystal planes in combination with a ripening process driven by the thermodynamics.The annealing treatment in Ar/H2creates porous monodispersed VS2（H-VS2）,which is subsequently integrated with graphene oxide to form porous monodispersed H-VS2/rGO composite coupled with a reduction process.As an anode material for LIBs,H-VS2/rGO delivers superior rate performance and longer cycle stability:a high average capacity of 868/525 mAh g-1 at a current density of 1/10 A g-1;a reversible capacity of 1177/889 mAh g-1 after 150/500 cycles at 0.2/1 A g-1.Such excellent electrochemical performance may be attributed to the increased active sites available for lithium storage,the alleviated volume variations and the shortened Li-ion diffusion induced from the porous structure with large specific surface area,as well as the protective effect from graphene nanosheets.