Necklace‐Like Structures Composed of Fe3N@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 Fe3 N@C yolk-shell particles as an advanced anode for Na-ion batteries is reported. In this electrode, every Fe3 N@C unit has a novel yolk-shell structure, which can accommodate the volumetric changes of Fe3 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 Fe3 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 .