Coupling of NiSe2 with MoSe2 confined in nitrogen-doped carbon spheres as anodes for fast and durable sodium storage.

On account of the relatively high theoretical capacity and lamellar structure, MoSe 2 is considered as an advanced anode material applied for sodium-ion batteries (SIBs). Unfortunately, the notorious issues of MoSe 2 including low electrical conductivity, tendency to restack and aggregate and high mechanical stress during cycling usually lead to the rapid deterioration of sodium storage properties. Herein, we propose the rational design and fabrication of NiSe 2 nanoparticles decorated flower-like MoSe 2 nanosheets simultaneously confined in N-doped carbon spheres (denoted as MoSe 2 -NC/NiSe 2) via successive solvothermal and selenization steps. The heterostructure as generated between NiSe 2 and MoSe 2 can effectively provide more rich redox chemistry and synergistic merits. Meanwhile, the derived N-doped carbon matrix can protect the MoSe 2 nanosheets from agglomeration, facilitate the electron transport in the composite, and accommodate the volume variation with the help of unique porous structure. Accordingly, the hybrid composite of MoSe 2 -NC/NiSe 2 presents a high capacity of 315 mAh g−1 at 1 A g−1 and high-rate feature with 146 mAh g−1 even over 2000 cycles at 5 A g−1, demonstrating the excellent sodium storage performance including fast charging/discharging and outstanding cycling durability when applied in SIBs. • The N-doped carbon prevents agglomeration of nanosheets and enhances the electron transfer ability. • The heterostructure provides more electroactive sites and increased (100) interlayer spacing of MoSe 2. • The hybrid composite of MoSe 2 -NC/NiSe 2 anode shows durable cyclic stability and outstanding rate capability. [ABSTRACT FROM AUTHOR]