Nano FeSb₂S₄ Anchored on Exfoliated Graphite for Sodium-Ion Battery Anode via a Two-Step Fabrication

FeSb2S4 is considered a potential anode material of sodium-ion batteries (SIBs) due to the high theoretical capacity (877 mAh g-1) and fast Na+ diffusion kinetics. Synthesis of the FeSb2S4-based anode via a simple strategy is essential for practical applications. In this study, nano FeSb2S4 anchored on exfoliated graphite (FeSb2S4-G) was fabricated via a two-step strategy: heat treatment of commercial FeS+Sb2S3 powder and then ball-milling with commercial graphite. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations reveal that the pulverized nano FeSb2S4 and exfoliated graphite establish the chemical bonds, which is very advantageous to boost the charge/discharge reversibility. As-prepared FeSb2S4-G delivered 577 mAh g-1 in the second cycle under 100 mA g-1 and kept 385 mAh g-1 in the 70th cycle; the cycling stability surpassed bulk FeSb2S4 (662 mAh g-1 in the 2nd cycle, 109 mAh g-1 in the 70th cycle). Considering only two steps of the synthesis processes, this work presents a viable strategy for fabricating high-performance FeSb2S4-based SIB anode materials.