Surface Anionization of Self-Assembled Iron Sulfide Hierarchitectures to Enhance Capacitive Storage for Alkaline-Metal-Ion Batteries

Due to the ever-growing demand for cost-effective batteries toward greener and sustainable applications, continuous effort has been devoted to tailoring the interfacial kinetics of electrode materials. Herein, surface anionization has been introduced for the hierarchical assembly of iron sulfides on three-dimensional (3D) graphene foam (denoted FeS₂@3DGF and FeS@3DGF). The surface-anchored sulfate species provide ideal electroactive sites, which is correlated with enhanced capacitive contribution and boosted energy storage. Consequently, remarkable rate capability and stable cyclability can be achieved in alkaline-metal-ion batteries. Specifically, FeS@3DGF displays superb cycling stability when evaluated as anodes for Li-ion batteries (a steady capacity of 1109 mAh g^-1 after 200 cycles at 200 mA g^-1). Moreover, superior rate capability can be achieved for Na-ion batteries (203 mAh g^-1 at 10※000 mA g^-1). These findings provide new insights into reinforcing interface kinetics during electrochemical processes and hold great promise for versatile applications in the future.