In-situ N-doped ultrathin MoS2 anchored on N-doped carbon nanotubes skeleton by Mo-N bonds for fast pseudocapacitive sodium storage

As one of the most promising anode materials in sodium ion batteries (SIBs), MoS2 has been severely hindered its wide application in the field of energy storage due to the low electronic conductivity and severe volume variation during charge/discharge. Herein, we propose and synthesize an innovative structure of ultrathin N-doped MoS2 nanosheets anchored on hollow N-doped carbon nanotube skeleton by Mo-N bonds (N-MoS2@NCNT). It is demonstrated that the N atoms decomposed from NH4+ ions after annealing in-situ substitute the basal S atoms in MoS2 structure to form N-doped MoS2 (N-MoS2), which improves the conductivity of the materials. Moreover, the stable Mo-N bonds between N-MoS2 and carbon skeleton keep the structural integrity of the electrode. With these merits, the N-MoS2@NCNT electrode shows high reversible capacity of 504.1 mAh g–1 with the ultrahigh capacity retention of 104.4 % after 100 cycles at 0.1 A g–1. The structural engineering of in-situ nitrogen doping combined with the tight chemical bonds between active material and carbon can significantly increase the electrochemical performance of MoS2. This strategy also provides an original idea for the next step of designing high-performance transition metal sulfide/carbon-based composites anodes for SIBs.