Vacancy engineering in MoS2 nanolayers coupled with dual-carbon confinement for potassium storage

Abstract

Molybdenum disulfide (MoS₂) has gained a lot of interest as a potassium storage material with a high anode capacity. However, the slow reaction kinetics and its highly unstable structure prevent the full realization of its electrochemical performance during the insertion and extraction of K⁺. Herein, sulfur vacancy-modified MoS₂ nanolayers grown coaxially with an external carbon coating and internal carbon nanotube support (denoted as C–MoS_2−x@CNTs) are designed as anode materials for potassium storage. This unique structure enables fast K⁺ reaction kinetics facilitated by S vacancy engineering, uniform growth of MoS₂ nanolayers controlled by internal carbon nanotubes, and the stability of the complete electrode preserved by the encapsulation of carbon. Therefore, the prepared C–MoS_2−x@CNTs reveal a high rate performance value of 180.9 mA h g⁻¹ (5 A g⁻¹) with a reversible capacity value of 323.8 mA h g⁻¹ (50 mA g⁻¹). It sustains a capacity of 141.2 mA h g⁻¹, exhibiting excellent cycling stability, even after 300 cycles at a current density of 2 A g⁻¹.