Liquid Phase Synthesis And Lithium Ion Properties Of Transition Metal Oxide With Specific Morphology

Developing and exploring reusable clean energy resources become very urgent and necessary due to fast increasing of population, climate warming, and large consume of fossil energy resources in the world. Nowadays, many types of clean energy resources have been developed, wherein, lithium-ion batteries （LIBs） become one of excellent and popular energy storage systems due to their high specific energy density. As we know that, transition metal oxides act as anode materials in LIBs owing to their high specific theory capacity, easy to synthesis, low-cost, environmental friendly and therefore receive great attention. We can modulate the structure, morphology, and surface microstructure of the transition metal oxides to better improve the storage-energy performances of the anodes in LIBs, which can provide a chance for realizing the enhancement of the collective storage-lithium features and applications for anode materials in LIBs.Based on the transition metal oxides as research objects, we synthesize and investigate the storage-lithium performances of three transition metal oxides with specific morphology via liquid-phase synthetic methods. The thesis can provide some new research methods and strategy for other metal oxides materials, detailed as following: 1. We report that the novel dumbbell-like Co₃O₄ superstructure can be obtained via calcination of the prepared spindle-like CoCO₃ precursor. Results demonstrated that the Ascorbic acid play a key role in directing the formation of the dumbbell-like superstructure during the synthetic process. The prepared dumbbell-like Co₃O₄ displays good crystalline nature, high specific surface area ～162.7 m2g^-1 and narrow pore-size-distribution-3.54 nm. When applied as an anode materials in LIBs, dumbbell-like Co₃O₄ based anode delivers as high as specific capacity of 1719 mA h/g for initial discharge, and remains low discharge capacity loss over 200th cycles at 0.1 C, even at 1 C and 5 C conditions, the present electrochemical performances are much superior to most previously reported data.2. We utilize hydrothermal treatment method to prepare α-Fe₂O₃@RGO nanocomposite and further study its lithium properties. This synthetic strategy without adding any other reduced agent, for large-scale synthesis of α-Fe₂O₃@RGO nanocomposite provided a simple, environmental friendly method. When used as anode in LIBs, α-Fe₂O₃@RGO anode even at a higher current density of 2000 mA g^-1 it can deliver capacity as high as 387 mA h g^-1. The results indicate the material manifests high cycle performance.3. We propose hydrothermal and calcination process to prepare Co₃O₄ hollow sphere with copper foam as the substrate. When used as anode in LIBs, Co₃O₄ anode can deliver a high capacity of 844 mA h g^-1 over 100th at 0.1 C. The results indicate this substrate composite material has good electrical chemical properties and rate properties.