Embedding CoS₂ nanoparticles in N-doped carbon nanotube hollow frameworks for enhanced lithium storage properties

The construction of metal sulfides-carbon nanocomposites with a hollow structure is highly attractive for various energy storage and conversion technologies. Herein, we report a facile two-step method for preparing a nanocomposite with CoS₂ nanoparticles in N-doped carbon nanotube hollow frameworks (NCNTFs). Starting from zeolitic imidazolate framework-67 (ZIF-67) particles, in situ reduced metallic cobalt nanocrystals expedite the formation of the hierarchical hollow frameworks from staggered carbon nanotubes via a carbonization process. After a follow-up sulfidation reaction with sulfur powder, the embedded cobalt crystals are transformed into CoS₂ nanoparticles. Benefitting from the robust hollow frameworks made of N-doped carbon nanotubes and highly active CoS₂ ultrafine nanoparticles, this advanced nanocomposite shows greatly enhanced lithium storage properties when evaluated as an electrode for lithium-ion batteries. Impressively, the resultant CoS₂/NCNTF material delivers a high specific capacity of ~937 mAh·g^–1 at a current density of 1.0 A·g^–1 with a cycle life longer than 160 cycles.