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Synthesis of the Sheet-Self-Assembled Flower-like LiMnPO4and ZnO Nanostructures and Their Application in Li-ion Battery

Author: LiFeng
Tutor: XuGang
School: Zhejiang University
Course: Materials Science and Engineering
Keywords: lithium-ion battery LiMnPO4 ZnO carbon coating solvothermal
CLC: TM912
Type: Master's thesis
Year: 2014
Downloads: 2
Quote: 0
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Abstract


Lithium ion battery electrode materials nanocrystallization will be helpful not only to shorten the lithium ion diffusion path, but to prevent performance degradation caused by volume change pulverization in the process of charging and discharging. In order to obtain the lithium ion battery electrode materials with excellent properties, the author did systemic research on the preparation and electrochemical properties of the sheet-self-assembled flower-like nanostructures of olivine structure LiMnPO4battery anode materials and transition metal oxides anode materials ZnO, and made the following important results:Using ethylene glycol solvent-thermal, the author successfully prepared the sheet-self-assembled dumbbell flower LiMnPO4nanomaterials with excellent electrochemical performance. The author also studied the influence of different proportion of water/ethylene glycol, reaction temperature, reaction time, acid ions on the synthesis of particle size and morphology of LiMnPO4, found that ethylene glycol solvent and acid radical ion play a key role in the synthesis of sheet-self-assembled dumbbell flower-like LiMnPO4nanostructures. As a result of ethylene glycol and acetic acid ion selective adsorption, the layered olivine structure LiMnP04crystallizes into flake, then self-assembles to dumbbell flower nanostructures. It is found that pure ethylene glycol as solvent, under the condition of230℃, solvent thermal above56h, the formed sheet-self-assembled dumbbell flower-like LiMnPO4materials own maximum crystallization and specific surface area. So it has the best electrochemical performance after carbon coating, with capacity of122.29mAh/g for the first time in0.05C current ratio in the discharge, and remains91.55%after100cycles.Under the assistance of sodium citrate, tetramethyl ammonium or sodium hydroxide as mineralizer, the sheet-self-assembled flower-like ZnO nanomaterials were realized. TAMH, NaOH and sodium citrate were studied on the influence of the synthesis of ZnO morphology. It has found that the organic ions introduced from TAMH and sodium citrate of selective adsorption (1-120) lead to the formation of ZnO nanoparticles. In order to reduce the system energy, ZnO nanosheet self-assembled to form flower-like nanostructures. Under the function of TAMH and sodium citrate, the sheet-self-assembled flower-like ZnO has the thinnest nanosheet, is helpful for Li+to emergence-embedded and spread, thus has more excellent electrochemical performance after carbon-coating, Under the current ratio of0.5C, the first time discharge capacity is1239mAh/g, and it remains381mAh/g after30cycles.

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CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Battery
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