In Situ Construction of 3D Interconnected FeS@Fe₃C@Graphitic Carbon Networks for High‐Performance Sodium‐Ion Batteries

Iron sulfides have been attracting great attention as anode materials for high‐performance rechargeable sodium‐ion batteries due to their high theoretical capacity and low cost. In practice, however, they deliver unsatisfactory performance because of their intrinsically low conductivity and volume expansion during charge–discharge processes. Here, a facile in situ synthesis of a 3D interconnected FeS@Fe 3 C@graphitic carbon (FeS@Fe 3 C@GC) composite via chemical vapor deposition (CVD) followed by a sulfuration strategy is developed. The construction of the double‐layered Fe 3 C/GC shell and the integral 3D GC network benefits from the catalytic effect of iron (or iron oxides) during the CVD process. The unique nanostructure offers fast electron/Na ion transport pathways and exhibits outstanding structural stability, ensuring fast kinetics and long cycle life of the FeS@Fe 3 C@GC electrodes for sodium storage. A similar process can be applied for the fabrication of various metal oxide/carbon and metal sulfide/carbon electrode materials for high‐performance lithium/sodium‐ion batteries.