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The Research On Preparation Of Pure And Doped Layered Lithium Manganese Oxide

Posted on:2015-03-27Degree:MasterType:Thesis
Country:ChinaCandidate:H Z HuFull Text:PDF
GTID:2251330428958757Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
With the extensive application of lithium-ion batteries, layered lithium manganeseoxide(LiMnO2) have become one of the most attractive cathode materials for its advantages,such as rich manganese resources, low toxicity, high capacity (285mAh/g) and so on. But thestudy of LiMnO2still stops at the laboratory. The shortcomings for high production cost,structural instability and poor electrochemical cycling performance, impede thecommercialization of LiMnO2. This paper focused on providing a theoretical basis forcommercialization of LiMnO2and improving its electrochemical performance through theoptimization of mature technology, exploration of new preparation process for LiMnO2andthe doped sample. The details have been summarized as follows:(1) Orthogonal o-LiMnO2have been synthesized via hydrothermal synthesis method.The impacts of Li/Mn mole ratio, temperature and time of hydrothermal method have beenstudied. The results show that the purity of o-LiMnO2has become higher with the increases ofLi/Mn mole ratio, the reaction temperature and time. It was found that the best Li/Mn molarratio is4:1and the best temperature is180℃.(2) Unit and dual Al, Mg, Y, Ni, Cr, S doped LiMnO2have been synthesized viahydrothermal synthesis method. The results show that unit doped sample synthesized byhydrothermal method is feasible, however, dual doped sample has complex chemicalmechanism during the process of synthesis. Further study are needed.(3) Orthogonal o-LiMnO2have been prepared by mechanical alloying. The impacts ofgrinding-ball/material ratio, Li/Mn molar ratio, the control agents and milling time have beenresearched. The results show that the mechanical alloying method can prepare pure o-LiMnO2at lower Li/Mn molar ratio (1.5:1) conditions.(4) Monoclinic m-LiMnO2have been prepared by hydrothermal-ion exchange method.The lithium source, Na/Mn mass ratio, reaction temperature and reaction time have been studied. The results show that the hydrothermal method, compared with distillation, cansuccessfully achieve ion exchange in a relatively short period of time in synthesis ofm-LiMnO2. It was found that lithium salt plays a key role in the structure of the product.
Keywords/Search Tags:Lithium-ion batteries, LiMnO2, doping, mechanical alloying
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