Rational Design of 3D Hierarchical Fe₃S₄ for Superior Sodium-Ion Battery Anode Material

Among various transition metal sulfides, iron-based sulfides have attracted wide attention due to their abundant resources, low cost, and non-toxicity, showing considerable research value in the field of secondary batteries. Thereinto, Fe₃S₄ has a high theoretical specific capacity of 785 mAh g⁻¹. However, at present, the research related to Fe₃S₄ anode for sodium-ion batteries (SIBs) is still in its infancy, and it also suffers from severe volume expansion and limited preparation. Therefore, to further boost its sodium storage potential, the Fe₃S₄@rGO composite with hierarchical structure and carbonaceous network is proposed in this study. Beneficial from the ingenious hierarchitectures and flexible graphene coating, the Fe₃S₄@rGO anode exhibits outstanding sodium storage performance, which can deliver a high capacity of 603 mAh g⁻¹ after 1500 cycles with a superior capacity retention of 98%. The micron flower-like structure composed of 2D nanosheets can provide sufficient active sites and promote the rapid transport of Na⁺. Meanwhile, the 3D interconnected graphene carbon network makes a crucial contribution to alleviating volume changes and enhancing electrical conductivity. This work reveals the application potential of Fe₃S₄ as an anode electrode for SIBs and provides available insights for the development of other electrode materials.