The Controllable Preparation Of Carbon Supported Vanadium Disulfide Composite And Its Application In Aqueous Zinc-ion Battery

The aqueous-based zinc-ion battery has the advantages of high specific capacity,abundant raw material reserves and high electrolyte safety,which is considered to be the main energy storage device to replace lithium-ion batteries in the future.However,the existing cathode materials for aqueous-based zinc-ion batteries are far from reaching the goal of excellent performance.The previous exploration of cathode materials are mainly focused on manganese dioxide and Prussian blue analogs.However,the Mn-O material has poor performance and rapid capacity decay,while the prussian blue analogs has a lower capacity(about 50 m A h g^-1).The vanadium disulfide has great advantages as a cathode material because of its large interlayer spacing,high conductivity and easy synthesis.In this thesis,vanadium disulfide and its composite materials were prepared by Liquid phase method as cathode materials for aqueous zinc-ion batteries.Their electrochemical properties were detailed studied.The specific research contents are as follows:(1)Preparation of high loading VS₂@CP(Carbon paper)growth electrode and its electrochemical performanceUsing high-conductivity carbon paper as the growth substrate of vanadium disulfide,the VS₂@CP growth electrode was prepared by hydrothermal method(the anchoring effect of carbon paper makes the vanadium disulfide nanosheets grow regular).This chapter focuses on the influence of two electrode preparation methods,VS₂slurry coated electrode(grinding will destroy the structure of vanadium disulfide nanosheets)and VS₂@CP growth electrode.The morphology,structure and integrity of vanadium disulfide nanosheets will be discussed.The test results show that the prepared high-load(8.3 mg/cm²)VS₂@CP growth electrode has better zinc ion storage performance,mainly including high reversible capacity(156.8 m A h/g under 0.1 A/g)and good cycle performance(200 cycles at 0.5 A/g to maintain 139.6 m A h/g).(2)Preparation of ultra-high loading VS₂@CC(Carbon cloth)growth electrode and its electrochemical performanceUsing high-conductivity carbon cloth as the growth substrate of vanadium disulfide,the VS₂@CC growth electrode was prepared by hydrothermal method.By controlling the treatment time of the carbon cloth,three types of carbon cloth with different hydrophilicity(normal,good,and excellent)were obtained.Vanadium disulfide with different morphology and structure on the above three carbon cloths can be obtained by hydrothermal approach.It was found that the stronger the hydrophilicity of the carbon cloth,the higher the loading capacity,and the better the zinc ion storage performance can be achieved.Vanadium disulfide was grown on a carbon cloth with excellent hydrophilicity,and the effect of hydrothermal time(morphology and structure changes with time)on the loading capacity and zinc ion storage performance was focused on.The study found that the electrode with high loading capacity(9.5 mg cm^-2)at 3 hours of hydrothermal has the highest mass specific capacity(retaining 144 m A h/g under 0.5 A/g for 200 cycles);at 9 hours of hydrothermal,it is over The high-load(12.6 mg cm^-2)electrode has the highest area specific capacity(up to 1.64 m A h/cm²at the 50th cycle at 0.5 A/g).(3)Preparation of carbon nanotube vanadium disulfide composite material and its electrochemical performanceThe carbon nanotube vanadium disulfide composite material is prepared by hydrothermal method(the carbon nanotube network is macroscopically covered with vanadium disulfide nanosheets).Carbon nanotubes play a supporting role on alleviating volume expansion,and their one-dimensional structure has a large specific surface area,which allows the electrode material to fully contact the electrolyte and provides more reaction sites.In addition,its tubular structure can speed up the diffusion of zinc ions and improve the conductivity of the material.This chapter compares the VS₂single electrode with the CNT/VS₂composite electrode,focusing on the series of effects produced by carbon nanotubes and their influence on the storage performance of zinc ions.The research results show that the prepared CNT/VS₂composite electrode has better zinc ion storage performance,mainly including high reversible capacity(171.5 m A h/g at 0.1 A/g)and good cycle performance(200 cycles at 0.5 A/g to Maintain 160 m A h/g).