Stimulating the Reversibility of Sb2S3 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 Nb2O5 layers to restrict the sulfur species and facilitate them to form sulfides reversibly is proposed. Taking Sb2S3 anode as an example, Sb2S3 and Nb2O5 are dispersed in the core and shell layers of carbon nanofibers (C NFs), respectively, constructing core@shell structure Sb2S3-C@Nb2O5-C NFs. Benefiting from the bi-functional Nb2O5 layers, the electrochemical reversibility of Sb2S3 is stimulated. As a result, the Sb2S3-C@Nb2O5-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@Nb2O5-C NFs electrode. Encouraged by the stimulated reversibility of Sb2S3 and SnS2 anodes, other sulfides with high electrochemical performance also could be developed for KIBs.

Automated summary

A strategy using Nb2O5 layers to confine sulfur species and facilitate reversible sulfide formation was proposed, leading to improved K-ion storage properties in Sb2S3 and SnS2 anodes. This approach demonstrated the highest K-ion diffusion coefficient, longest cycling stability, and excellent rate capability among controlled electrodes, showing potential for developing high-performance sulfides for KIBs.