Abstract: A series of MoS2 thin films were prepared by RF magnetron sputtering with MoS2 as the sputtering target at different sputtering powers. The films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), and the structural and morphological changes of the films during the cycling process and their effects on the cycling performance of the cells were investigated. The results show that the prepared films are S-rich MoS2 amorphous films; SEM analysis shows that the distribution of S and Mo elements in the films is uniform and there is no bias aggregation; XPS analysis shows that there is a single S phase in the prepared films, and the content of single S phase in the overall films is about 14% (atomic fraction). During the initial charge/discharge cycle, these uniformly distributed single S reacts with Li+ to form lithium polysulfide, resulting in irreversible loss, thus forming a uniformly distributed porous structure in situ, which can effectively alleviate the volume expansion in the subsequent cycles of the film and increase the specific surface area of the active material, which is conducive to improving the specific capacity and cycling stability of the film. When the target power is 100 W, the specific capacity of the film electrode is 429.8 mAh/g after 20 cycles, and the specific capacity can still be maintained at 420.4 mAh/g after 300 cycles, showing good cycling stability.

DOI: 10.3969/j.issn.1001-9731.2020.08.016