Electrode performance of amorphous MoS3 in all-solid-state sodium secondary batteries

All-solid-state Na–S secondary batteries that use sodium and sulfur, both available in abundance, are the most attractive next-generation batteries. In this study, two types of amorphous MoS₃ (a-MoS₃) were prepared as electrode active materials for use in all-solid-state sodium secondary batteries using the thermal decomposition (TD) of (NH₄)₂MoS₄ and mechanochemical (MC) processes, denoted a-MoS₃ (TD) and a-MoS₃ (MC), respectively. X-ray diffraction, thermogravimetric-differential thermal analysis, and X-ray photoelectron spectroscopy (XPS) analyses revealed that a-MoS₃ (TD) and a-MoS₃ (MC) had different local structures. The a-MoS₃ (TD) and a-MoS₃ (MC) electrodes showed high reversible capacities of 310 mAh g⁻¹ and 260 mAh g⁻¹, respectively, for five cycles in all-solid-state sodium secondary batteries. XPS analysis of the discharge–charge products suggested that the dissociation and formation of disulfide bonds occurred during the discharge–charge reaction. The results show that a-MoS₃ is a promising active electrode material for all-solid-state sodium batteries.