Preparation And Performance Of Vanadium-Based Cathode Material For Lithium/sodium-ion Batteries

Lithium-ion battery is a storage device model of charge and discharge, with high capacity, long service life, safety and environmental protection and other advantages. It has been widely favored in the 21 st century, the handheld and wearable devices become more delicate and light, there is a demand for lithium ion batteries with higher energy density and smaller volume. On the other hand, with the development of large energy storage devices, the existing reserves of lithium resources may not meet the needs of social development. The development of high additional value of vanadium products is important to the energy resource structure and economic development of our country. In this paper, we prepared vanadium compounds by developing through hydrothermal method and explored their performance as cathode materials for lithium/sodium ion battery.In first chapter, we introduce the characteristics, structure and working principle of lithium/sodium-ion battery. we also introduce the current development directions of lithium ion batteries and the background of this thesis is presented.Second chapter mainly introduced experimental drugs and instruments. We briefly introduce the working principle of the instrument and the test method of electrochemical performance. Then, we describe assembling process of coin-type cells.We had synthesized Na₂V₆O₁₆ nanowires materials using V₂O₅ and Na₂SO4 as raw materials and by hydrothermal method, which researched as lithium ion battery cathode materials for the application. There were a series of characterization for Na₂V₆O₁₆, such as XRD, SEM, TEM, FTIR, and TGA. We fabricate Na₂V₆O₁₆ and carbon black（NaVO/CB） or multi-walled carbon nanotube（NaVO/MWCNTs） composite flexible electrode use vacuum filtration method and we test electrodes on the performance of lithium ion battery. The results show that the sample has better cycling stability compared with the electrode without thermal treatment, the capacity retention rate was 75.3%（thermal treatment） and 48.1%（without thermal treatment） at the 150 mA g^-1 after was 100 cycles.Herein, a rationally assembled 3D architecture of 1D V₂O₅ nanoribbons（V₂O₅ NR） with 2D reduced graphene oxide（RGO） sheets has been developed by a one-step hydrothermal method using RGO and the prepared Na₂V₆O₁₆ samples as raw materials.The binder-free V₂O₅ NR/RGO flexible electrode as a high performance cathode material for sodium-ion batteries were fabricated by a simply vacuum-filtering method. Furthermore, the flexible electrode exhibit high capacity, superior cyclic stability and rate performance. As cathode in sodium-ion batteries, the material has a specific capacity of 145 mAh g^-1 at the current rate of 800 mA g^-1, which retain 91.7% after 200 cycles.Finally, a brief summary is given and the prospects are discussed in Chapter 5.