Synthesis Of MOF-based Binder-free Electrode Material And Study On Its Electrochemical Properties

The increasing demand of electrochemical energy conversion,storage applications and environmental protection make sustainable and renewable energy resources and the related energy generation,storage,and conservation technologies attract intense attention in recent years.Supercapacitors,due to their high-power density,fast charge and discharge rate and long lifespan,have been widely concerned in hybrid vehicles and electronic devices as a type of efficient energy storage device.The microstructure of metal-organic framework materials is exactly what an ideal energy storage material needs,but the metal-organic framework materials have poor conductivity and stability,and cannot usually be directly used for electrode materials.A simple and effective method is needed Converted into excellent materials for energy storage.In this paper,several cobalt-based metal-organic framework materials were used as precursors,and several electrode materials for supercapacitors were prepared through modification treatment,and the structure and morphology characterization and electrochemical performance tests were performed.The experimental work and results are as follows:1.We have grown two metal-organic framework materials,NH₂-Co-MOF and Co-MOF,directly on a nickel foam substrate by solvothermal method.After characterization,we found that both materials have the microstructure of nanosheets and are extremely thin,which is very conducive to the growth of secondary structures.Then we performed electrochemical performance tests on the NH₂-Co-MOF/Ni electrode and Co-MOF/Ni electrode.At a current density of 1A/g,the mass specific capacity of the NH₂-Co-MOF/Ni electrode was 472C/g.In contrast,Co-MOF/Ni electrodes have no electrochemical performance.So,we choose NH₂-Co-MOF/Ni electrode as the precursor for the subsequent modification treatment in the next chapter.2.In order to improve the electrochemical activity of the NH₂-Co-MOF/Ni electrode synthesized in the previous chapter,we used a hydrothermal method to hydrolyze it with nickel ions.We use different gradients of hydrothermal time to grow secondary materials on the surface of nanosheets to obtain layered nickel-cobalt hydroxide electrodes with different properties.After electrochemical tests,the optimal performance of the NiCo-LDH/Ni electrode is that at a current density of 1A/g,the mass specific capacity of the NiCo-LDH/Ni electrode is 1021C/g.It is compared to NH₂-Co-MOF/Ni electrode,performance has more than doubled.3.We have grown CoO on a nickel foam substrate by hydrothermal method and annealing treatment,and then directly etch CoO on nickel foam with dimethylimidazole at room temperature to obtain ZIF-67,and then vulcanize to obtain CoS/CoO/Ni electrode.Through the vulcanization of different temperature gradients,we obtain the optimal performance of the CoS/CoO/Ni electrode:at a current density of 1A/g,the mass specific capacity of the CoS/CoO/Ni electrode is 795C/g.