Synthesis of CoS 2 Nanoparticles/Nitrogen‐Doped Graphitic Carbon/Carbon Nanotubes Composite as an Advanced Anode for Sodium‐Ion Batteries

Cobalt sulfide (CoS 2 ) is a promising anode material for high‐performance sodium‐ion batteries (SIBs) because of its low cost, excellent electrical conductivity, and high theoretical capacity. The practical implementation of a CoS 2 anode, however, is still hindered by fast capacity decay and low power density caused by its huge volume expansion during the charging/discharging process. Herein, we developed a low‐cost, facile and large‐scale method to fabricate a nitrogen‐doped carbon‐layer‐constrained structured CoS 2 /carbon nanotubes (NC@CoS 2 @CNTs) hybrid with a novel morphology for high‐performance SIBs. The hybrid electrode has reversible specific capacities of 669 and 334 mAh g −1 at the current densities of 200 mA g −1 and 5000 mA g −1 , respectively, and an unprecedented cycling stability of approximately 0.014 % capacity decay per cycle over 1000 cycles at 3000 mA g −1 . The balanced high electrochemical performance for the hybrid electrode can be attributed to the synergetic effect among the CoS 2 nanoparticles, N‐doped carbon coating and in situ grown CNTs. The results demonstrate that the CoS 2 can be well utilized with the N‐doped carbon/carbon nanotubes hybrid material structure, which provides a facile approach to realize excellent performance for practical applications.