Transition-metal dichalcogenides (TMDs) such as MX₂ (M = Mo, W, Nb, Ta, etc. and X = S, Se, etc.) are becoming useful for energy storage applications. Among these, molybdenum disulfide (MoS₂), has emerged as a promising candidatedue to its exceptional electrical, physicochemical, and mechanical properties. Bulk MoS₂ has a layered crystal structure consisting of stacked S-Mo-S monolayers separated by approximately 0.62 nm interlayer spacing, with strong covalent Mo-S bonds and weak Van der Waals forces between adjacent monolayers. Due to their high specific surface area and flexibility, mono or layered MoS₂ nanosheets have superior electrochemical properties than bulk MoS₂.

In this work we present a simple single-step ultrasonic exfoliation technique for producing layered MoS₂ nanosheets from bulk MoS₂ powder. The two major concerns of chemical exfoliation i.e. usage of highly flammable chemicals and yield production have been eliminated in this process. Using LiBr and toluene for exfoliation, almost 70% yield was achieved. Various physiochemical characterizations were performed for both non-ultrasonicated and ultrasonicated MoS₂. In case of ultrasonicated sample, studies were performed on the basis of time, i.e. the sample was collected after every hour of exfoliation for up to 3 hours. The peak broadening of the XRD profiles confirmed successful exfoliation, suggesting formation of nanosized layered structure from the bulk MoS₂.

The Li-ion battery performance of MoS₂ as anode material was further investigated for all the exfoliated samples. All the electrochemical investigations were carried out in coin cell device configuration. The specific capacitance for pristine MoS₂, 1, 3 and 5 h exfoliated samples were calculated, the maximum specific capacity observed was 65 mAh g^-1, 100 mAh g^-1, 186 mAh g^-1, 513 mAh g^-1 respectively, at 1 A g^-1 current density. An enhancement of about 110% from bulk to 5 h exfoliated sample was observed. Further, the effect of exfoliated sample as anode material was investigated for Na ion batteries, which along with higher specific capacitance also exhibited high rate capability and excellent cycling stability. Therefore just by simple and cost effective exfoliation technique we establish the advantages of MoS₂ as next generation high-end energy storage material.