Preparation And Research On Energy Storage Mechanism Of Cobalt-based Electrode Material For Supercapacitors

In the context of rapid energy consumption and environmental pollution,electrochemical energy storage is of great significance.Cobalt-based materials have high tantalum capacitance and electrochemical catalytic properties.Co?OH?₂ is a typical supercapacitor electrode material with high theoretical specific capacity and environmental friendliness,but capacity and cycle stability need to be improved.At the same time,Co?OH?₂ can easily grow into a regular two-dimensional sheet,which is the ideal stencil material.In this paper,the preparation of cobalt-based materials is carried out,and the hydrothermal reaction model is optimized.The prepared Co?OH?₂ electrode material has high capacitance performance and cycle stability.In addition,Co?OH?₂ is sacrificed by sacrificial template method.The Co?OH?₂ successfully transformed into CoTe@Co₄B composite nanosheet array,and studied its electrochemical energy storage performance.The main work of the thesis is as follows:1:Using a common hydrothermal reaction model,the two reaction precursors were separated by a Celgard membrane,and a high-load,high-purity Co?OH?₂ array was successfully prepared by membrane permeation.Different from the traditional hydrothermal system,the improved hydrothermal system reduces the large-area contact of the reactants,reduces the rapid decrease of the concentration of the reaction products in the solution,and achieves stable and uniform growth of the electrode material.In addition,we explored the effect of ethanol on the permeability of Celgard membranes,and successfully controlled the microscopic morphology of Co?OH?₂ by increasing the permeability of Celgard membranes by ethanol.Electrochemical tests showed that the Co?OH?₂ array prepared by adjusting the Celgard film with 5 mL of ethanol had optimal specific capacity and long cycle stability.An asymmetric supercapacitor assembled using the prepared Co?OH?₂ as a positive electrode material and commercial activated carbon as a negative electrode material has high energy density,power density,and long cycle stability.2:The Co?OH?₂ nanosheet array was prepared on carbon cloth by electrodeposition technique.Then the CoTe@Co₄B composite structure was successfully prepared by one-step hydrothermal reaction.The effect of reaction time on the electrochemical performance of CoTe@Co₄B composite structure was investigated.Electrochemical tests show that CoTe@Co₄B material prepared by hydrothermal reaction for 12 h has higher surface capacitance performance at low current density,while CoTe@Co₄B prepared by hydrothermal reaction for 24 h shows more at high current density.The high area specific capacity is superior to the Co?OH?₂ nanosheet array and the CoTe@Co₄B electrode material.In addition,the prepared CoTe@Co₄B was used as the positive electrode,the commercial activated carbon was used as the negative electrode,and assembled into an asymmetric supercapacitor,which exhibited high power density and energy density,and the capacity did not show significant attenuation after 4000 cycles,demonstrated excellent long cycle stability.