Facile preparation of MoS2/few layer graphene composites by plasma-enhanced ball milling for potassium-ion batteries

Abstract

Potassium-ion batteries (PIBs) display significant potential for large-scale energy storage systems, attributed to their high energy density. Molybdenum disulfide (MoS₂), with its high theoretical capacity and 2D layered structure, is an ideal anode material for K⁺ intercalation/deintercalation in PIBs. However, the low electronic conductivity and substantial volume changes during K⁺ insertion/extraction inherently limit the performance of MoS₂. A plasma-enhanced ball milling process has been employed to synthesize MoS₂/few-layer graphene (FLG) composites, achieving mechanical exfoliation and MoS₂-FLG bonding in a single step. The synthesized MoS₂/FLG composite material significantly benefits from the exceptional electrical conductivity and excellent mechanical properties of FLG. This results in outstanding K⁺ storage performance. Notably, it demonstrates an impressive rate capacity of 184 mAh g^-1 at a high current density of 1.6 A g^-1. Additionally, the material exhibits outstanding cyclic stability, maintaining a capacity of 323 mAh g^-1 over 200 cycles at a current density of 0.1 A g^-1. The mechanism of the conversion reaction of MoS₂ during the electrochemical cycling process has been elucidated through ex situ X-ray photoelectron spectroscopy (XPS). More importantly, this research introduces an effective strategy for synthesizing multi-component composites, where plasma facilitates material exfoliation and binding between different components.