High-Capacity Sb/Fe₂S₃ Sodium-Ion Battery Anodes Fabricated by a One-Step Redox Reaction, Followed by Ball Milling with Graphite

Antimony (Sb) has been considered a promising anode forsodium-ionbatteries (SIBs) owing to its high theoretical capacity (660 mA hg(-1)) and low redox voltage (0.2-0.9 V vsNa(+)/Na). However, the capacity degradation caused by thevolumetric variation during battery discharge/charge hinders the practicalapplication. Herein, guided by the DFT calculation, Sb/Fe2S3 was fabricated by annealing Fe and Sb2S3 mixed powder. Next, Sb/Fe2S3 was blendedwith 15 wt % graphite by ball milling, yielding nano-Sb/Fe2S3 anchored on an exfoliated graphite composite (denotedas Sb/Fe2S3-15%). When applied as an anode ofSIBs, Sb/Fe2S3-15% delivered reversible capacitiesof 565, 542, 467, 366, 285, and 236 mA h g(-1) atcurrent rates of 1, 2, 4, 6, 8, and 10 A g(-1), respectively,surpassing most of the Sb-based anodes. The co-existence of highlyconductive Fe2S3 and Sb minimizes the polarizationof the anode. Our experiments proved that the Sb and Fe2S3 phases were reversible during discharge/charge cycling,and the exfoliated graphite can accelerate the Na+ diffusionand e(-) conduction. The proposed synthesis methodof this work can also be applicable to synthesize various antimony/transitionmetal sulfide heterostructures (Sb/M1-x S), which may be applied in a series of fields.