Amorphous MoS Derived from (NH)MoS: Structural Insights and Applications in All-Solid-State Batteries.

Amorphous molybdenum polysulfides (a-MoS) have attracted considerable attention because of their unique physical and chemical properties, which enable their use in a wide range of applications including energy-storage materials. Among various synthesis methods, thermal decomposition provides an effective route for synthesizing a-MoS. In particular, amorphous molybdenum trisulfide (a-MoS) prepared via thermal decomposition has emerged as a promising active material for energy-storage applications owing to its unique structural and electrochemical characteristics. However, owing to its amorphous nature, the detailed structure of a-MoS remains unclear. In this study, a-MoS was synthesized via thermal decomposition of (NH)MoS, and its structure and electrochemical properties were investigated. It was revealed that a-MoS exhibited an amorphous nature with a MoS-like structure but without disulfide bonds. Moreover, in the a-MoS structure, Mo was coordinated with more than six sulfur atoms and at least two sulfur species with different electronic states were identified. The presence of sulfur with high binding energy would likely contribute significantly to the high electrochemical capacity as an active material in batteries. All-solid-state lithium cells using a-MoS exhibited high reversible capacities of approximately 313 mAh g and excellent cycling stability over 3000 cycles, demonstrating that a-MoS is a promising high-performance active material.