Vanadium Oxides Based Micro-nanostructures:Synthesis And Applications In Energy Storage

The goal of this dissertation is to explore the controllable synthesis of vanadium>xides based micro-nanostructures with favorable morphologies by analyzing the;rystal structural characteristics and property of the target products. We also leveloped new approaches to improve the performances of the micro-nanostructures n applications of being used as materials for aqueous lithium ion batteries, supercapacitors, and the corresponding structure-property relationships have also been nvestigated, which are useful for studying new functional materials in the future. The details are summarized briefly as follows:1. We developed a facile mild hydrothermal route to synthesize layered structured CUV2O5single-crystal nanobelts, which is a new anode material for aqueous lithium ion batteries. The thorough investigations of the intermediate processes indicated that considerable hydrated protons co-intercalated into the layer space of the CUV2O5nanobelts accompanying with the lithium ions inserting, accounted for the fast fading of the capacity, which can be smothered at appropriately higher pH value. The adjusting of the pH value was found to be an effect way to improve the cycle stability of CUV2O5.2. We successfully synthesized the tunnel structured VO2(B) nanorods and W doped V02(B) nanoflowers assembled by thin nanosheets under a hydrothermal condition. The structures and morphologies of the VO2(B) nanorods and the W doped VO2(B) were investigated through the characterizations of XRD, SEM, TEM, HRTEM and XAFS. The test results of the aqueous lithium ion batteries revealed that the sample of W doped VO2(B) exhibited higher capacity retention rate during the300cycles.3. We prepared the nanohybrids of ultra thin V2O5nanosheets and graphene by using vanadium tri-isopropoxy oxide as a special V source and GO as the structure oriented template in a hot solution of absolute ethanol. The detailed results of the optimizing experiments demonstrated the oriented rule of the GO in the forming of the nanocomposites. The sample was assembled as symmetric ultraflexible all-solid-states-thin supercapacitors, which exhibited good performance in the charge and discharge processes.4. We obtained K2V6O16·1.5H2O superlong nanobelts, which were confired to be one new kinds of room-temperature ferromagnetism (RTFM) semiconductors with one dimensional nanostructures. The formation mechanism of the K2V6O16·1.5H2O nanobelts was revealed crystally and high anisotropy led to better conductivity along the growth direction. Both the calculations based on the density functional and the corresponding experimental results demonstrated that the RTFM resulted from the oxygen vacancies produced during the solution process. These insights give a better understanding of the RTFM and such nanobelts providing structure units for fabricating multifuctional nanodevices in the future.