Stimulating the Reversibility of Sb S 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 Nb O layers to restrict the sulfur species and facilitate them to form sulfides reversibly is proposed. Taking Sb S anode as an example, Sb S and Nb O are dispersed in the core and shell layers of carbon nanofibers (C NFs), respectively, constructing core@shell structure Sb S -C@Nb O -C NFs. Benefiting from the bi-functional Nb O layers, the electrochemical reversibility of Sb S is stimulated. As a result, the Sb S -C@Nb O -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 is kept at 0.1 A g after 100 cycles, and a negligible capacity degradation (0.03% per cycle) at 2.0 A g for 2200 cycles is delivered). The enhanced K-ion storage properties are also found in SnS -C@Nb O -C NFs electrode. Encouraged by the stimulated reversibility of Sb S and SnS anodes, other sulfides with high electrochemical performance also could be developed for KIBs.