Preparation Of Manganese Oxide Cathode Materials For Lithium-ion Battery And Its Electrochemical Performance Study

Nanomaterials of manganese oxide have been widely researched and applied in lithium ion secondary batteries due to their low cost and environmentally benign nature. In this paper, layered structureδ-MnO2 with nanowire morphology, Li2Mn03 material and MnxCoyNi1-x-yO material with sphere morphology have been controllablly synthesized. Their structure and morphology have been characterized by XRD, SEM and TEM, and the electrochemical property has also been studied.This paper mainly consists of three sections:reviewer (ChapterⅠ), experiments (ChapterⅡ, ChapterⅢand ChapterⅣ) and conclusion (ChapterⅤ).ChapterⅠreviews the mechanism and feature of lithium ion second batteries, the development trend of the positive electrode materials for lithium ion secondary battery, the crystal structure and synthesis menthod of manganese oxides with different structures and morphologies. The research purpose is also discussed.In ChapterⅡ, by using KMnO4 and C3H6O (epoxypropane) as raw materials,δ-MnO2 with layered structure and nanowire morphology is synthesized through a facile hydrothermal route without any surfactants and templates. By changing the reaction time, reaction temperature and the content of C3H6O solution, the optimism fabrication parameters ofδ-MnO2 with layered structure and nanowire morphology have been studied. The research results indicated that the content of C3H6O solution and hydrothermal treatment temperature have an obvious influence for the morphology and structure of the obtained final products.δ-MnO2 with layered structure and nanowire morphology exhibits an ideal capacitive behavior and good cycling behavior. Meanwhile,δ-MnO2 with layered structure and nanowire morphology also shows good discharge capacity and better cycle performance.In ChapterⅢ, Li2Mn03 material is synthesized through a facile hydrothermal route, and the effect of the Li/Mn molar ratio on the structure and morphology for the obtained materials is also investigated. The research results indicated that the Li/Mn molar ratio influences the morphology and structure of the final products. Li2Mn03 material exhibits good discharge capacity and better cycle performance.In ChapterⅣ, by hydrothermal treating a mixed solution of nickel acetate, manganese acetate, cobalt (Ⅱ) acetate and citric acid, MnxCoyNi1-x-yO cathode material with sphere morphology is synthesized, and their structure and electrochemical property are also investigated. The research results indicated that the reaction time and reaction temperature have an obvious influence for the morphology and structure of the final products. MnxCoyNi1-x-yO cathode material with sphere morphology exhibits good discharge capacity and better cycle performance. In ChapterⅤ, the research conclusion is obtained on the basis of the experimental results.