Vanadium Oxides Based Micro-nanostructures: Synthesis And Applications In Aqueous Lithium Ion Batteries

The goal of this dissertation is to explore the controllable synthesis of vanadium oxides based micro-nanostructures with favorable morphologies by understanding the crystal structural characteristics of the target products and developing novel chemical reaction routes. On the basis of the unique microscopic crystal structures, new application of these vanadium oxides based micro-nanostructures has been further developed as active anode materials for aqueous lithium ion batteries, and the corresponding structure-property relationships have been also investigated in this dissertation. The details are summarized briefly as follows:1. We successfully synthesized new-phased metastable V₂O₃ porous urchin-like micro-nanostructures by a simple top-down precursor-pyrolyzation strategy. The generation of new phase and preparation of porous morphology were simultaneously realized by using functional ligand in precursor molecules. We introduced these new-phased metastable V₂O₃ micro-nanostructures as active anode materials for aqueous lithium ion batteries, realizing the application of vanadium (III) oxides in this electrochemical energy storage and conversion system for the first time.2. We developed an available pathway to accomplish the synthetic montroseite VOOH hollow nanourchins with typical tunneled crystal structure after sixty years of delay. Paramontroseite VO₂ with same morphology was converted from montroseite VOOH through a topochemical transition strategy due to the extreme structural similarity revealed by crystal structure analysis. We investigated their electrochemical properties as anode materials for aqueous lithium ion batteries, further expanding the application of vanadium oxides based compounds with low valence in this research area.3. We investigated the charge-discharge reaction mechanism of aqueous lithium ion batteries for the first time by taking a new anode material of single-crystalline Ag₂V₄O₁₁ nanobelts as an example on the basis of its typical layered crystal structure. A two-step reaction mechanism was proposed and the reason for rapid capacity fading was also deduced.4. We successfully demonstrated the crystallographic pillar effect on cyclability enhancement for aqueous lithium ion batteries by comparing the electrochemical cycle performance of a new anodeβ-vanadium bronze Ag_0.33V₂O₅ nanowires with 3D tunneled structure and Ag₂V₄O₁₁ nanobelts with 2D layered structure. The significant role of this pillar effect was further verified by an extension of another new anode material of Na_0.33V₂O₅ nanowires.