Application Of Lithium/sodium Secondary Batteries Based On Mof Materials And Derivatives

With the development of electronic information technology,humans have begun to pursue a wider range of needs.Among them,new energy storage equipment has become the focus of human attention,and lithium/sodium secondary batteries as a new generation of energy materials have achieved Energy storage for electric vehicles and large-scale power grids.This paper focuses on the direction of lithium/sodium-ion battery and lithium-sulfur battery electrode materials,and gradually solves the problems between basic research and practical application of electrode materials.It is known that current commercial lithium/sodium ion batteries use graphite as a negative electrode material,while graphite electrodes limit the development of lithium/sodium ion batteries due to their low capacity.Therefore,exploring new electrode materials has become the focus of current research,among which metal oxide/sulfide has become one of the candidate materials due to its high theoretical capacity.However,the problem of poor conductivity and volume expansion is also a problem with lithium-sulfur batteries.Recently,a metal organic framework（MOF）material having a porous structure has entered people’s field of vision and has been extensively studied.This carbon material based on MOF porous structure can effectively solve the problems of electrical conductivity and volume expansion of metal oxides/sulfides,and also improve the stability of the material through modification.For lithium sulfur batteries,the porous structure of MOF can be used to limit the"shuttle effect"of sulfur.The specific study includes the following three parts:（1）A new type of carbon-coated gallium sulfide composite was prepared by using gallium MOF as a precursor material,post-synthesis modification and vulcanization treatment.Leverage the proven"self-healing"properties of gallium during the lithiation process,solve the problem of structural instability in long cycles,and modify the introduced organic ligands（BTC）to replace solvent sites in MOF to improve the carbon framework,which mechanical properties can limit the volume expansion problem during lithiation.When applied to the anode material of lithium/sodium ion battery,it significantly improves the stability of the electrode and obtains excellent electrochemical performance.（2）The sulfur particles are partially confined in ZIF-67 by melt diffusion,and at the same time,the sulfur particles exposed on the outer surface are uniformly coated with Mn O₂ nanoparticles by a simple method.The potassium benzyl group on the ZIF-67organic ligand is converted into a carboxyl group by using potassium permanganate,and the formed manganese dioxide is coated on the outer surface.The experimental results show that when applied to lithium-sulfur batteries,the ZIF-67@S@Mn O₂ cathode material retains the specific capacity of 484 m Ah g^-1 for 100 cycles at 2 C current density,and the Coulomb efficiency is close to 100%.（3）The imidazole ligand on the zeolite imidazole framework（ZIF-4）is also a good precursor for post-synthesis modification.The hydrogenation reaction of carbene on ZIF-4 imidazole is carried out,and the new group Cu Cl₂ is introduced to replace the position of hydrogen to obtain the modified ZIF-4-Cu Cl₂.The alkalization and thermal decomposition treatment of the introduced group Cu Cl₂ can be carried out.Preparation of nano copper oxide particles.The electrochemical results show that the ZIF-4@CuO composite has good electrochemical performance and maintains a specific capacity of 424m Ah g^-1 for 300 cycles at a current density of 1000 m A g^-1 at high current,and it is still possible to observe the completeness of the frame of the material after 100 cycles by SEM.