Two-dimensional (2D) transition-metal dichalcogenide materials show potential for use in alkali metal ion batteries owing to their remarkable physical and chemical properties. Nevertheless, the electrochemical energy storage performance is still impaired by the tendency of aggregation, volume, and morphological change during the conversion reaction and poor intrinsic conductivity. Until now, ultrathin molybdenum disulfide nanosheets with a metallic-phase structure on the inner surface of mesoporous hollow carbon spheres (M-MoS2@HCS) have rarely been investigated as an anode for sodium-ion batteries. In this work, a novel M-MoS2@HCS anode was designed and synthesized by employing a template-assisted solvothermal reaction. Structural and chemical analyses indicate that the M-MoS2 nanosheets with a larger interlayer spacing compared to their semiconductor counterpart grow on the inner surface of HCS via covalent interactions. When used as the anode materials for Na+ storage, the M-MoS2@HCS anode presents durable and rapid sodium storage properties. The developed electrode shows a reversible capacity of 291.2 mAh g–1 at a high current density of 5 A g–1. After 100 cycles at 0.1 A g–1, the reversible capacity is 401.3 mAh g–1 with a capacity retention rate of 79%. After 2500 cycles at 1.0 A g–1, the electrode still delivers a reversible capacity of 320.1 mAh g–1 with a capacity retention rate of 75%. The excellent sodium storage capability of the MoS2@HCS electrode is explained by the special structural design, which reveals great potential to accelerate the practical applications of transition-metal dichalcogenide electrodes for sodium storage.

No abstract

Thanks to the low cost and earth's abundant potassium resources, potassium ion batteries (PIBs) have attracted much interest as alternative energy storage devices. However, there is still a great challenge...

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.

No abstract