2022 Volume 130 Issue 4 Pages 308-312
All-solid-state sodium secondary batteries have garnered significant attention as next-generation batteries with high safety. To realize an all-solid-state sodium secondary battery with a high energy density, it is necessary to develop a high-capacity electrode active material. In this study, we prepared amorphous molybdenum polysulfide (a-MoSx, x = 3–7) using a mechanochemical process as electrode active material in all-solid-state cells using Na3PS4 sulfide electrolyte. In all-solid-state cells, a-MoS3, a-MoS4, a-MoS5, a-MoS6, and a-MoS7 showed high reversible capacities of 260, 330, 470, 540, and 510 mAh g−1, respectively. X-ray photoelectron spectroscopy analyses suggested that the discharge–charge reaction in a-MoSx proceeds mainly by anion redox with dissociation and formation of disulfide bonds. Amorphous sulfur-rich MoSx is thus a promising electrode active material with high capacity in all-solid-state sodium batteries.