Stimulating the Reversibility of Sb₂ S₃ Anode for High-Performance Potassium-Ion Batteries

Conversion-alloy sulfide materials for potassium-ion batteries (KIBs) have attracted considerable attention because of their high capacities and suitable working potentials. However, the sluggish kinetics and sulfur loss result in their rapid capacity degeneration as well as inferior rate capability. Herein, a strategy that uses the confinement and catalyzed effect of Nb₂ O₅ layers to restrict the sulfur species and facilitate them to form sulfides reversibly is proposed. Taking Sb₂ S₃ anode as an example, Sb₂ S₃ and Nb₂ O₅ are dispersed in the core and shell layers of carbon nanofibers (C NFs), respectively, constructing core@shell structure Sb₂ S₃ -C@Nb₂ O₅ -C NFs. Benefiting from the bi-functional Nb₂ O₅ layers, the electrochemical reversibility of Sb₂ S₃ is stimulated. As a result, the Sb₂ S₃ -C@Nb₂ O₅ -C NFs electrode delivers the rapidest K-ion diffusion coefficient, longest cycling stability, and most excellent rate capability among the controlled electrodes (347.5 mAh g^-1 is kept at 0.1 A g^-1 after 100 cycles, and a negligible capacity degradation (0.03% per cycle) at 2.0 A g^-1 for 2200 cycles is delivered). The enhanced K-ion storage properties are also found in SnS₂ -C@Nb₂ O₅ -C NFs electrode. Encouraged by the stimulated reversibility of Sb₂ S₃ and SnS₂ anodes, other sulfides with high electrochemical performance also could be developed for KIBs.