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⁺, S₂²⁻, 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.