Construction of CoS-encapsulated in ultrahigh nitrogen doped carbon nanofibers from energetic metal-organic frameworks for superior sodium storage

Metal-organic frameworks (MOF) derived carbon nanomaterials are arising as promising anode materials for sodium-ion batteries. However, the heteroatoms loss and aggregation during pyrolysis significantly hamper its further application. Herein, we utilized electrospinning structuring energetic MOF into nanofibers, followed by one-step sulfurization. The high content N doping (24.58 wt%) and CoS nanoparticles encapsulated carbon nanofibers with ultra-large interlayer distance (0.422 nm) were synthesized, which improved the diffusion properties and phase behavior of sodium ions. The resulting CoS/NSCNF (NSCNF for nitrogen and sulfur co-doped carbon nanofibers) delivered a superior rate performance of 358.5 mAh g −1 after 2250 cycles at 6 A g −1 , serving as an anode for sodium-ion battery. The excellent storage performance ascribed to abundant N/S defects, enlarged carbon spacing, and the continuous one-dimensional structure of CoS/NSCNF, enhancing sodium ions storage ability contrasted with MOF-derived carbon. The density functional theory calculations further demonstrate that nitrogen-doping favors sodium ion adsorption ability of CoS/NSCNF, thereby improving storage performance. The high content N doping (24.58 wt%) and CoS nanoparticles embedded carbon nanofibers with ultra-large interlayer distance (0.422 nm) were synthesized by electrospinning and a one-step sulfurization process. The resulting CoS/NSCNF are presented as anode materials of SIB, delivered long-term cycling stability and superior rate performance of 358.5 mAh g −1 after 2250 cycles at 6 A g −1 .