Cu9S5-nanowire-pinned-WS2 sheets on hollow cubic carbon for synergistic promotion in K-ion battery performance

Tungsten disulfide (WS2) presents a layered structure with a high theoretical capacity (433 mA h g−1) in potassium-ion batteries, making it a promising anode material. However, its kinetics is poor with limited practical capacity and it is still a challenge to design new structures to improve its kinetics. In this work, a hollow Cu9S5/C/WS2 composite structure is designed. It is used as an anode in potassium-ion batteries (PIBs) with a high reversible capacity (406 mA h g−1 after 150 cycles at 200 mA g−1) and excellent rate performance (246 mA h g−1 at 20 A g−1). These results are attributed to its unique hollow composite structure, where the WS2 sheets are pinned on hollow cubic carbon by Cu9S5 nanowires. On one hand, the introduction of Cu9S5 nanowires expands the layer spacing of WS2 and forms a K+ fast diffusion channel. On the other hand, hollow carbon and Cu9S5 nanowires form a fast electron transmission path, which improves the charge transport rate. Additionally, the use of hollow carbon and Cu9S5 nanowires as a framework enhances structural stability. The synergistic effect of these aspects finally realizes fast and stable K+ storage. This work provides a new insight into the design of high-performance potassium storage devices using layered metal sulfides.