Ultrathin Metallic-Phase Molybdenum Disulfide Nanosheets Stabilized on Functionalized Carbon Nanotubes Via Covalent Interface Interaction for Sodium- and Lithium-Ion Storage

Two-dimensional (2D) ultrathin MoS2 nanosheets, owing to their abundant active sites, tunable interlayer space, and favored ion and mass diffusion, show promise as anode materials for energy storage. However, the low electronic conductivity due to the intrinsic semiconductor structure (2H-MoS2), the spontaneous aggregation caused by the large van der Waals force between layers, and the huge volume alteration during the entire reaction hinder the practical applications of MoS2-based anodes. Here, by employing a facial solvothermal approach, we uniformly disperse metallic-phase MoS2 (1T-MoS2) nanosheets on the functionalized carbon nanotube (CNT) surface to form a 1D@2D hierarchical architecture. The obtained CNT@1T-MoS2 composites show strong covalent interface interaction and improved electronic conductivity. The distinct phase layout, morphology, and component impart the CNT@1T-MoS2 electrode with outstanding sodium-storage performance. The CNT@1T-MoS2 electrode retains a capacity of 542.3 mA h g(-1) at 0.1 A g(-1) after 50 cycles. Even at a large current density of 20 A g(-1), the electrode still gives a high capacity of 153.4 mA h g(-1). Moreover, when it is applied in lithium storage, the CNT@1T-MoS2 electrode also possesses good stability with a capacity up to 913.5 mA h g(-1) experiencing 50 cycles at 0.1 A g(-1) as well as satisfactory fast-charging capability (613.6 mA h g(-1) at 5A g(-1)). This work shows that controlling the phase structure and interface interaction is effective to boost the application of transition-metal dichalcogenide-based composite electrodes in energy storage and conversion.