Preparation Of Transition Metal Oxides Materials Applied In Li-ion Battery

In order to meet the growing energy needs and to avoid the depletion of globalresources and long-term damage to the environment, seeking high performance, lowcost and environmental friendly energy system becomes urgent problems at present. Asthe clean energy, lithium ion batteries has high efficiency with high energy density andgood cycle performance, thus becames one of the most reliable choice to replacetraditional fossil fuels. At present the mainly commercialized lithium ion battery anodematerial is graphite. But graphite has low theoretical capacity (only372mAh g-1),safety problem and other issues, so researchers have to seek new materials with highertheoretical capacity and more safety. In recent years, the scientists pay more and moreattention to looking for new anode materials with good safety, high theoretical capacity,and longer cycle life. However, the metal oxide anode materials precisely have theseadvantages. So it is the ideal of lithium ion battery cathode material to replace graphite.Researches show that, through the nano, special morphology and the fluid growthmethods can effectively increase the electrical conductivity of the material and reliefmaterials volume expansion in the process of charging and discharging, thuseffectively improve the electrochemical properties. In this thesis, metal oxide materialswere synthesised by a facile solvothermal hydrothermal method. The structure andphysical properties of synthetic materials were characterized by modern analyticaltechniques, such as XRD, SEM, TEM, BET and TGA and XPS, et al. And we exploredthe metal oxide nanomaterials application in lithium ion batteries. The main researchcontents and results are as follows:(1) The second chapter of the paper, we introduced the synthesis of a specialtremella-like porous thin sheet structure, which is with a simple low temperaturehydrothermal reaction for the first step and then further annealing. At the currentdensity of0.1C, the first discharge capacity of tremella-like NiO was1374mAh g-1.And after30cycles, the reversible capacity still remain at30mAh g-1, which showedthe well cycle performance.(2) In the third chapter, we introduced the structure synthesis, and lithium ionbattery performance of mesoporous ZnCo2O4micro ball materials. SEM and TEMresults showed that the globular structure was composed of many nanoparticlessecondary stack, whose size was about10nm. Lithium ion battery tests indicated that the structure could alleviate ZnCo2O4the volume effect in the cycle process, and couldmaintain the stability of the structure.(3) In the fourth chapter, We used one-step hydrothermal method to directly insitu growth ZnCo2O4nanoarrays materials on nickel foam substrate. Electrochemicaltest results showed that the material we composed had high capacity and good cyclestability. And under high current density, it can still maintain a high capacity and highstability.