Necklace‐Like Sn@C Fiber Self‐Supporting Electrode for High‐Performance Sodium‐Ion Battery

Sodium‐ion battery (SIB) is regarded as the next generation of large‐scale energy storage systems, but it still faces problems such as low energy density, severe expansion/contraction of electrode volume, and poor cycle performance. Herein, necklace‐like Sn‐MOF@PAN fibers are prepared by the electrospinning method and then carbonized into Sn‐C necklace paper as the binder‐free cathode in an SIB. In each bead, Sn nanoparticles are wrapped by a porous carbon shell. The morphology and composition of the necklace‐shaped Sn@C nanofibers are optimized by adjusting the ratio of Sn‐MOF/PAN in the precursor. Sn@C with the optimal composition has a high specific capacity of 207 mAh g −1 even at a high current density of 2 A g −1 and maintains a specific capacity of 327 mAh g −1 after 100 cycles at a current density of 100 mA g −1 . This research provides a high‐performance flexible electrode for SIBs.