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Research On The Vanadium-Based Cathode Materials For Zinc Ion Battery

Posted on:2021-01-01Degree:MasterType:Thesis
Country:ChinaCandidate:G SuFull Text:PDF
GTID:2381330611967693Subject:Chemical engineering
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Human’s excavation and consumption of energy on the earth is getting stronger and stronger,resulting in fewer and fewer non-renewable energy reserves,such as fossil energy.According to the statistics of relevant institutions,nowadays,with the development rate of the world and the rate of energy consumption,that fossil fuels such as crude oil and natural gas will be exhausted in the next few decades.Especially since the beginning of the 21st century,the prominence of energy demand has become more and more obvious.The energy crisis is not only for a country,but for the entire world,and is a problem that the global human society needs to face and urgently need to solve.Therefore,it is urgent to look for renewable new energy.Aqueous zinc ion batteries(AZIBs)are considered to be the substitutes for the next generation of energy storage systems because of their low cost,simple preparation process,and the advantage that the electrolyte solution is not harmful to the environment.However,due to zinc ion diffusion kinetics and other reasons,it is still a very challenging task to find suitable anode materials for aqueous zinc ion batteries with high rate performance,long cycle life,and excellent low temperature electrochemical performance.The lowproduction cost and high specific capacityof vanadium-based oxides,and the synthesis method is simple.These advantages have attracted a large number attention of scientific researchers.In this paper,three AZIBs cathode materials of potassium vanadate(KVO),sodium vanadate(NVO),and lithium vanadate(LVO)were synthesized in one step by simple hydrothermal method,and three alkali metal ions(K+,Na+,Li+)were inserted into theinterlayer of vanadium pentoxide(V2O5)which acts as a“pillar”to protect the layered structure of V2O5during the charge/discharge process of cathode.This method can effectively increase the layer spacing of thestructure of the host,thus improving the rate performance,cycle stability and low temperature electrochemical performanceof thepositive electrode of ZIBs.The specific contents of this article are as follows:(1)This article first explains the research background of the subject and an overview of zinc ion batteries(ZIBs),including the development history and current research status of ZIBs,elaborating the components,advantages and disadvantages of ZIBs,and the research status of common cathode materials.It briefly explains the thoughts and research contents of this article.(2)The central idea of the thesis explains in detail the synthesis methods and steps of KVO,NVO,LVO and the discussion and analysis of the experimental data results.It is proposed that KVO has the best electrochemical performance among the three positive electrode materials.The reason is that K+has a smaller electronegativity in the main material,and the main structure is more stable.In addition,when it is embedded in the V2O5layer,it can expand more.Large interlayer spacing to ensure that zinc ions can more easily enter the material for repeated insertion/extraction.From the result,the room/low-temperature performance of K+pre-intercalated layered V2O5(KVO)is better than most of the cathodes.Specifically,the KVO delivers a high capacity of 251 m A h g-1at 5 A g-1after 1000 cycles.Even at a low temperature of-20 oC,the high reversible capacities of 241 and 115 m A h g-1at 1 and 5 A g-1can be obtained after 1000 cycles.This article uses X-ray diffraction,X-ray photoelectron spectroscopy,and scanning electron microscopy to carefully explore the reaction mechanism and structural stability of the KVO cathode.The three materials prepared in this subject not only have good electrochemical behavior at room temperature,but also have a very stable and high-efficiency capacity output at-20℃,which makes them incompetent in the competition of secondary batteries At the same time,the method of introducing alkali metal ions into the V2O5layer to stabilize its structure also provides a reference for the future research of zinc ion battery cathode materials.
Keywords/Search Tags:aqueous electrolyte, zinc ion battery, solvothermal method, positive electrode, layered material, alkali metal ion
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