Preparation Of Bimetallic Oxides And Sulfides Derived From Metal-Organic Frameworks And Their Electrochemical Properties

Today’s era,the rapid consumption of non-renewable resources severely limits the sustainable development of society.Therefore,the development of renewable energy has become particularly urgent,and energy storage is the key to utilizing renewable energy.Supercapacitors have advantages such as fast charging and discharging and high power density in the field of energy storage,so they have attracted the attention of researchers.The development of electrode materials with high conductivity and capacitance is the key to achieving high-performance supercapacitor devices.This article takes MOF（metal-organic framework）derived bimetallic oxides and sulfides as the research direction.According to the characteristics of MOF materials,it synthesizes electrode materials with high specific surface area to improve the performance of supercapacitors.（1）In the first series,a nickel-cobalt-based metal-organic framework prepared by the solvothermal method was used as a template to synthesize core-shell spherical Ni Co₂O₄with different morphologies by controlling the calcination temperature.MOF has high porosity and specific surface area,which can shorten the ion transport path.The core-shell structure is more helpful to reduce the stress generated during the reaction and improve the cycle stability.Therefore,taking the NCO-450 sample synthesized at the optimal calcination temperature as an example,when the current density reaches 1 A g^-1,its specific capacitance is 668.2 F g^-1.After 5000 cycles of charging and discharging,it still retains 79.7%of its initial capacitance,showing excellent rate performance and cycle stability.（2）The second series,based on the first series of research,synthesized manganese-doped Ni Co₂O₄microspheres by efficient solvothermal method and high-temperature calcination.When tested as a supercapacitor electrode material,the material showed uniform distribution of Mn dopants and battery-like behavior.The NCO-0.3 sample with the optimal doping ratio showed an excellent specific capacity of 1221.2 F g^-1at a current density of 1 A g^-1.In addition,after 5000 cycles of charging and discharging at a current density of 10 A g^-1,it showed an excellent capacitance retention rate of 87.5%.（3）The third series,this series is based on the first series of experimental work,using solvothermal and vulcanization strategies,the Ni Co₂S₄microspheres are synthesized,and their vulcanized structure effectively ensures the structural stability of the electrode material at high current density and significantly improves the electrochemical performance.Compared with bimetallic oxides,it has a higher specific surface area.When the NCOS-7 synthesized with an appropriate sulfidation time was used as an electrode material,its specific capacity was 1961.8 F g^-1when the current density reached 1 A g^-1.At the same time,after 5000 cycles of charging and discharging at a current density of 10 A g^-1,it still showed an excellent capacitance retention rate of 83%.