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

Abstract

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.