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Obvious volume change and the dissolution of polysulfide as well as sluggish kinetics are serious issues for the development of high performance metal sulfide anodes for sodium-ion batteries (SIBs), which usually result in fast capacity fading during continuous sodiation and desodiation processes. In this work, by utilizing a Prussian blue analogue as functional precursors, small Fe-doped CoS2 nanoparticles spatially confined in N-doped carbon spheres with rich porosity were synthesized through facile successive precipitation, carbonization, and sulfurization processes, leading to the formation of bayberry-like Fe-doped CoS2/N-doped carbon spheres (Fe-CoS2/NC). By introducing a suitable amount of FeCl3 in the starting materials, the optimal Fe-CoS2/NC hybrid spheres with the designed composition and pore structure exhibited superior cycling stability (621 mA h g−1 after 400 cycles at 1 A g−1) and improved the rate capability (493 mA h g−1 at 5 A g−1). This work provides a new avenue for the rational design and synthesis of high performance metal sulfide-based anode materials toward SIBs. [ABSTRACT FROM AUTHOR]

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]

Hard carbon with large interlayer spacing is suitable as the anode material for sodium-ion batteries. Rape seed shuck derived lamellar hard carbon is synthesized through hydrothermal and pyrolysis processes. As the anode, it exhibited good cycling stability, delivering a capacity of 143 mAh g −1 after 200 cycles at 100 mA g −1 . The promising performances are attributed to the sheet structure with expanded interlayer distance (0.39 nm) and much void which can lower the sodium-ion insertion-extraction barrier and promote Na-ion diffusion and storage. The effect of pyrolysis temperature on the performance is also investigated. [ABSTRACT FROM AUTHOR]