Flower-like WS2@NS-C composite as a high-performance anode for Li-ion batteries

Abstract

As a typical layered metal sulfide with larger interlayer spacing and higher theoretical capacity than graphite anode, WS2 has become one of the candidate materials to replace graphite anode. However, there are still problems such as significant capacity loss caused by high volume variation in the cycling process, dissolution of polysulfides intermediates and unfavorable Li+ diffusion dynamics. In this paper, the WS2 nano-flowers obtained by the solvothermal method were used as the matrix, which was coated with polymerized pyrrole at ambient temperature, and then calcined to form flower-like WS2 @N, S-co-doped carbon (WS2 @NS-C) composite. The synergy of flower-like hierarchical construction and NS co-doped carbon network effectively improves the electron/ion transport kinetics, creates variety of pseudo-capacitive reaction active sites, and might buffer the volume variation during repeated lithiation/delithiation and inhibit dissolution of polysulfide. Thus, it reveals exceptional stability and rate performance, reaching a specific capacity of 969 mA h g−1 after cycling 100 times at 0.1 A g−1 and 633 mA h g−1 after cycling 1000 times at 1.0 A g−1. This exceptional Li storage characteristic is attributable to the combined function of its flower-like construction and NS co-doped carbon network.