English
【Research Background】
Although lithium-ion batteries have not yet reached the expected height in terms of energy density, they have been widely used in wearable electronics, electric vehicles and energy storage grids. Researchers have made some progress in the research and development of new materials to obtain high energy storage capacity without reducing power density and cycle stability. Two-dimensional materials are considered to be ideal electrode materials because of their high area-to-volume ratio, rapid electron transfer and optimized ion diffusion channels, which are very favorable to the kinetics of electrochemical reactions. MXene, in particular, as a typical representative of two-dimensional materials, has some unique advantages, such as metal conductivity, low lithium-ion diffusion barrier, and negligible volume changes during ion intercalation and detachment. However, MXene's application in lithium batteries is limited by its relatively low theoretical capacity (320 mAh g-1). In addition, the repacking problem caused by van der Waalz interaction and hydrogen bonding between MXene nanosheets will lead to a serious reduction in the accessible area, conductivity and active sites, which in turn will affect the energy storage capacity. Designing 2D nanosheets into 3D hollow structures is an effective way to alleviate the problem of heavy stacking.
The rapid transmission provides sufficient pore size and open transport channels, and this unique structure provides a new idea for the preparation of 2D nanosheet-based hollow materials.
【Introduction to Results】
【Introduction to achievements】
Recently, Professor Gengzhi Sun's research group of Nanjing University of Technology published a research paper in the internationally renowned academic journal Small: Electrostatically Assembling 2D Nanosheets of MXene and MOF-Derivatives into 3D Hollow Frameworks for Enhanced Lithium Storage. In this study, the negative 2D MXene nanosheet and the positive layered bimetallic hydroxide derived from ZIF-67 are recombined in a 3D hollow structure by electrostatic self-assembly in a simple and controlled way. After annealing, transition metal oxide @MXene (CoO/CoMo3O8@MXene) composite hollow electrode is used in lithium-ion batteries, and CoO/CoMo3O8 nanosheets can prevent the reaccumulation of MXene and provide ultra-high lithium storage performance. At the same time, MXene nanosheets can form a 3D conductive network with mechanical stability, which in turn promotes rapid electron transfer in the interface and limits the volume expansion of CoO/CoMo3O8 inside. This hollow structure provides a reversible capacity of 947.4 mAh g-1, excellent rate performance, and good cycling stability.
【Summary of this article】
In this paper, MXene nanosheets and MOF-derived LDH nanosheets were successfully synthesized by a simple electrostatic self-assembly method. In this structure, MXene nanosheets have excellent conductivity and negligible volume changes, while TMO nanosheets enhance the lithium storage properties of the composite. The layered structure prevents the reaccumulation of two-dimensional nanosheets, further improves the electrochemical kinetics, provides sufficient pore size and open transport channels for the rapid transport of ions, and this unique structure provides a new idea for the preparation of 2D nanosheet-based hollow materials.
