Necklace‐Like Structures Composed of Fe 3 N@C Yolk–Shell Particles as an Advanced Anode for Sodium‐Ion Batteries

It is of great importance to develop cost‐effective electrode materials for large‐scale use of Na‐ion batteries. Here, a binder‐free electrode based on necklace‐like structures composed of Fe 3 N@C yolk–shell particles as an advanced anode for Na‐ion batteries is reported. In this electrode, every Fe 3 N@C unit has a novel yolk–shell structure, which can accommodate the volumetric changes of Fe 3 N during the (de)sodiation processes for superior structural integrity. Moreover, all reaction units are threaded along the carbon fibers, guaranteeing excellent kinetics for the electrochemical reactions. As a result, when evaluated as an anode material for Na‐ion batteries, the Fe 3 N@C nano‐necklace electrode delivers a prolonged cycle life over 300 cycles, and achieves a high C‐rate capacity of 248 mAh g −1 at 2 A g −1 .