Synthesis Of Host-guest Structure ?-CD-MOF Derived Materials And Their Electrochemical Properties

Metal organic framework materials?MOFs?are widely used in energy conversion fields such as batteries and catalysis due to their controllable crystal structure,regular pores and large specific surface area.However,since most of the organic ligands commonly used to synthesize MOFs are expensive and toxic,the yield,cost,and safety issues brought about cannot be ignored.In recent years,a new type of MOF?CD-MOF?with cyclodextrin as a ligand has attracted great attention from researchers.Cyclodextrin not only has low toxicity,but because of its unique ring structure and internal hydrophobic-hydrophilic properties,it has become one of the most important host materials in supramolecular chemistry.In this paper,?-CD-MOF inclusion compounds and their derived carbon composite materials are used as research objects,combined with MOFs and host-guest chemical synthesis technology to construct carbon encapsulated oxide nanocomposites with a "pomegranate" structure,and explore the material structure and electricity and structure-activity relationship between chemical properties.For the first time,the microwave-assisted liquid phase method was used to synthesize the ?-CD-MOF inclusion compound with the host-guest structure,and the carbon composite material with the pomegranate structure was prepared by combining the high-temperature pyrolysis technology.The different guest molecules,modifiers,and sintering temperature were studied Etc.on the product morphology and structure.The study found that using the inclusion properties of ?-cyclodextrin,the metal organic salt can be evenly encapsulated into ?-CD-MOF crystals on the molecular scale,thereby achieving the nano-sized control of metal oxides in subsequent carbon encapsulated composite materials.The test results of the electrochemical performance of the material show that at a current density of 200 m A g-1,the initial discharge specific capacity reaches 400 mAhg^-1.As the number of cycles increases,the capacity gradually increases,and after 250 times It reaches 700 mAhg^-1 or more;at a current density of 1000 m A g-1,after 600 cycles,its discharge specific capacity can reach 600 m A h g,showing good lithium storage performance.In order to further improve the lithium storage performance of the prepared material,try to modify the material from three aspects: doping,compounding,and coating.The study found that: by introducing a dopamine coating layer in the inclusion compound,it can not only improve the conductivity of the material,but also alleviate the structural collapse of the MOF crystal during the pyrolysis process;further wash to remove part of the K-containing component,to achieve the material Secondary hole making.The structure-adjusted Co-OC/NC material showed better cycle stability and rate performance.At a current density of 1000 m A g-1,the specific discharge capacity stabilized at 495 mAhg^-1 after 600 cycles;when When the current density is increased to 5000 m A g-1,its specific capacity can still be maintained above 300 mAhg^-1.