Sb Ultra‐Small Nanoparticles Embedded within N, S co‐Doped Flexible Carbon Nanofiber Films with Longitudinal Tunnels as High Performance Anode Materials for Sodium‐Ion Batteries

Abstract Designing low‐cost carbon‐based anode with excellent electrochemical performance plays a vital role in the commercialization of sodium‐ion batteries (SIBs). However, its limited theoretical specific capacity and poor rate performance seriously affect its practical applications. Simply adjusting the morphological structure or component‐based regulation strategies cannot usually solve all problems efficiently. In response, one‐dimensional Sb 2 S 3 nanorods with the longitudinal distribution are used as a sacrificial template in this work by a simple electrostatic spinning method. After heat treatment, abundant longitudinal distribution channels within flexible carbon nanofibers are obtained. Meanwhile, Sb ultra‐small nanoparticles can be in‐situ embedded within N, S co‐doped carbon matrix (N,S,Sb‐CNFs). Owing to the N, S, Sb co‐modification and the well‐designed one‐dimensional mesoporous carbon substrate, the N,S,Sb‐CNFs hybrids achieve better interfacial contact with electrolyte, ameliorated electrical conductivity and distinct kinetic promotion. Furthermore, the undesired volume expansion of Sb nanoparticles during sodiation can also be efficiently suppressed. As expected, the N,S,Sb‐CNFs based half‐cell remains a reversible capacity of 287.8 mAh g −1 at 1 A g −1 even after 3500 cycles and harvests a capacity of 239.6 mAh g −1 at a high current density of 4 A g −1 , demonstrating excellent cycling stability and rate performance. Furthermore, the assembled flexible full‐cell matched with the Na 3 V 2 (PO 4 ) 2 O 2 F cathode also obtains superior bending resistance and continuous discharge ability during the deformation process, proving the potential of the flexible N,S,Sb‐CNFs electrode in practical applications.