Structure analyses of amorphous MoS3 active materials in all-solid-state lithium batteries

Abstract

We have successfully prepared amorphous MoS3 (a-MoS3) by ball milling a mixture of Mo metal and sulfur and investigated structural changes during the charge-discharge processes. The XPS measurements revealed that a-MoS3 should consist of Mo4+, S2 2?, and S2?. In the XRD profiles of the a-MoS3 electrodes after the initial discharge and charge tests, only the halo patterns due to the amorphous state were observed without crystalline diffraction peaks. The HR-TEM observations of a-MoS3 electrodes during the 1st discharge process revealed that the lattice fringes due to MoS2 layer structure disappeared gradually. However, the lattice fringes like MoS2 were also observed after the 1st charge. The HR-TEM image after the 10th charge did not show the lattice fringes of MoS2. These results of HR-TEM observations suggested that the reversible structural changes of a-MoS3 occurred.