Ultra-dispersed low-layer MoSe₂ materials for potassium ion batteries

A new research experiment is designed for the synthesis of ultra-dispersed MoSe₂ anode materials for use in potassium ion batteries. In this experiment, MoSe₂ with weak interlayer force is considered the research object, and two strategies are proposed to integrate the design principles of MoSe₂ anode materials. The first strategy involves the expansion and stripping of organic small molecules between MoSe₂ layers, and the other involves the induced assembly of MoSe₂ in the carbon skeleton. The ultra-dispersed structure of MoSe₂ material, coupled with the spatial-chemical dual confined mechanism of the carbon skeleton, helps address key problems such as electrode volume expansion, pulverization, and active component shedding. By integrating the above experimental design, the electrode material with high capacity, high rate, and long cycle can be obtained.

This experimental design involves two main steps: 1. To improve the structural stability of layered MoS₂ nanosheets, the MoS₂ is first combined with a carbon skeleton material. The carbon skeleton that is prepared using the salt crystal template method offers benefits such as large specific surface area, abundant pore structure, and adjustable surface chemical environment. Thus, it is an excellent carrier of active materials for electrode materials. Under solvothermal conditions, MoS₂ nanosheets can be self-loaded and uniformly dispersed in a carbon skeleton with abundant porous cavities. 2. To further improve the electrochemical performance of the MoS₂ material, small organic molecules are inserted into the MoS₂ layer structure to effectively expand the layer spacing of MoS₂. Small organic molecules with appropriate molecular size are selected, and according to their specific functional groups, they can be easily inserted into the Se-Mo-Se molecular layers under solvothermal conditions. The two aforementioned methods can effectively promote the rapid potassium storage behavior of the electrode material on the level of electrochemical reaction kinetics.

The morphology of the ultra-dispersed MoSe₂@carbon skeleton material helps retain the original frame structure of the carbon skeleton, and there is no obvious agglomeration phenomenon. In contrast, pure MoSe₂ materials exhibited obvious agglomerations, forming tight nanoclusters. From the high-resolution TEM images, it was observed that the pure MoSe₂ material exhibited clear lattice fringes, and more than 10 layers of Se-Mo-Se molecular layers are tightly stacked, with a layer spacing of approximately 0.67 nm. In the ultra-dispersed MoSe₂@carbon skeleton material, the MoSe₂ is stripped to 2–5 Se-Mo-Se molecular layers, and the layer spacing is 0.82 nm. The XRD and Raman data also confirm that the ultra-dispersed MoSe₂@carbon skeleton material exhibits a relatively low crystallinity, its layer spacing is also increased, and the number of Se-Mo-Se molecular layers is reduced. These results are consistent with the TEM data. The electrochemical data also showed that the ultra-dispersed MoSe₂@carbon skeleton material exhibited a significant improvement in terms of capacity, rate characteristics, and cyclic stability.

The good synergistic mechanism of carbon-skeleton-induced assembly and organic small molecule expansion can ensure the good structural stability of MoSe₂ materials. Additionally, it can improve the reaction kinetics characteristics of materials. This comprehensive experiment will provide a theoretical basis for the design of high-performance potassium ions storage anode materials and help students develop the ability to comprehensively apply theoretical knowledge in scientific research and solve practical problems.