Nanoflower-Like N-Doped C/CoS2 as High-Performance Anode Materials for Na-Ion Batteries

Novel N-doped nanoflower-like C/CoS2 spheres assembled from 2D wrinkled CoS2 nanosheets were synthesized through a facile one-pot solvothermal method followed by sulfurization. Ascribed to the optimized 3D nanostructure and rational surface engineering, the unique hierarchical structure of the nanoflower-like C/CoS2 composites showed an excellent sodium ion storage capacity companied with high specific capacity, superior rate performance and long-term cycling stability. Specifically, the conductive interconnected wrinkled nanosheets create a number of mesoporous structures and thus can greatly release the mechanical stresses caused by Na+ insertion/extraction. Besides, it was observed from the experiments that many extra defect vacancies and Na+ storage sites are introduced by nitrogen doping process. It was also observed that the crosslinked 2D nanosheets can effectively reduce the diffusion lengths of sodium ions and electrons, resulting in an outstanding rate performance (>700 mAh g-1 at 1 A g-1 and 458 mAh g-1 at even 10 A g-1) and extraordinarily cycle stability (698 mAh g-1 at 1 A g-1 after 500 cycles). The results provide a facile approach to fabricate promising anode materials for high-performance sodium-ion batteries (SIBs)