Structural regulation enabled stable hollow molybdenum diselenide nanosheet anode for ultrahigh energy density sodium...

For the continued use of sodium-ion batteries (SIBs), which require matching anode materials, it is crucial to create high energy density energy storage devices. Here, hollow nanoboxes shaped carbon supported sulfur-doped MoSe₂ nanosheets (S-MoSe₂@NC) are fabricated by in situ growth and heterodoping strategy. This ensures that the MoSe₂ nanosheets are tightly anchored to the nanoboxes carbon, and the structure can effectively buffer the volume stress caused by sodium ion (de)intercalation, as well as providing abundant ion/electron migration transportations. As anode for SIBs, the S-MoSe₂@NC shows a higher rate capability and excellent cycling stability (431.1 mAh/g after 1100 cycles at 10 A/g). This excellent cycle life and high rate ability are due to the structural stability and outstanding electronic conductance with reduced band gap of the S-MoSe₂@NC, as evidenced by the diffusion analysis and theoretical calculation. In order to promote the application of SIBs, the S-MoSe₂@NC and NaNi_1/3Fe_1/3Mn_1/3O₂ were assembled into a pouch cell, and the test found that besides the excellent cycle rate performance, the ultrahigh energy density of 256 Wh kg^-1 and flexible characteristics can be achieved. This study has proven that building a structure with a rock-steady foundation and quick ion migration may efficiently control sodium storage and pave the way for novel applications of high-performance transition metal dichalcogenides in sodium storage.