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

Abstract

On account of the relatively high theoretical capacity and lamellar structure, MoSe2 is considered as an advanced anode material applied for sodium-ion batteries (SIBs). Unfortunately, the notorious issues of MoSe2 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 NiSe2 nanoparticles decorated flower-like MoSe2 nanosheets simultaneously confined in N-doped carbon spheres (denoted as MoSe2-NC/NiSe2) via successive solvothermal and selenization steps. The heterostructure as generated between NiSe2 and MoSe2 can effectively provide more rich redox chemistry and synergistic merits. Meanwhile, the derived N-doped carbon matrix can protect the MoSe2 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 MoSe2-NC/NiSe2 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.