Fe₇S₈ Nanoparticles Embedded in Sulfur–Nitrogen Codoped Carbon Nanotubes: A High‐Performance Anode Material for Lithium‐Ion Batteries with Multilevel Confinement Structure

Fe 7 S 8 nanoparticle‐embedded sulfur–nitrogen codoped carbon nanotube composite (Fe 7 S 8 @CT‐NS) has been successfully designed as a high‐performance anode material for lithium‐ion batteries through a multistage confinement strategy. Constructed with a nitrogen‐doped carbon nanotube framework derived from melamine and a sulfurization process controlled via a polydopamine (PDA) intermediate layer, this composite features FeSC covalent bonding at the interface and a hierarchical porous structure. This multilevel confinement strategy integrates physical encapsulation within a nitrogen–sulfur codoped carbon framework and chemical stabilization via FeSC covalent bonding to synergistically enhance electrochemical performances. Electrochemical performance tests show that Fe 7 S 8 @CT‐NS retains a capacity of 527.9 mAh g −1 after 1000 cycles at a high current density of 5 A g −1 , demonstrating excellent reversibility and high‐rate performance across a wide current density range. This material, with its unique structural confinement, chemical bonding, and functional synergy, provides new insights into the development of high‐stability, high‐power lithium‐ion battery anode materials.