Few-layer WS2 nanosheets with oxygen-incorporated defect-sulphur entrapped by a hierarchical N, S co-doped graphene network towards advanced long-term lithium storage performances

Abstract

Tungsten sulfide (WS₂) with two-dimensional layered graphene-like structure as an anode for lithium-ion batteries (LIBs) has attracted large attention owing to its high theoretical capacity and unique S–W–S layer structure. However, it also always suffers from poor electrical conductivity and volume expansion during lithiation/delithiation process in the practical application. Herein, we demonstrate the successful synergistic regulation of both structural and electronic modulation by simultaneous oxygen incorporation in defect-sulphur WS₂ nanosheets embedded into a conductive nitrogen and sulfur co-doped graphene framework (denoted as O-DS-WS₂/NSG), leading to dramatically enhanced lithium storage. Such a unique structure not only increases the accessible active sites for Li⁺ and enhances the kinetics of ion/electron transport, but also relieves the volume effect of WS₂. Furthermore, the surface defects and heteroatom incorporation can effectively regulate the electronic structure, improve the intrinsic conductivity and offer more active sites. Consequently, electrochemical performance results demonstrate that the obtained O-DS-WS₂/NSG nanocomposites possess great application prospects in LIBs with high specific capacity, superior rate performance as well as excellent cycle stability.