Preparation And Electrochemical Properties Of LiMnO₂Cathode Materials With Doping-ion

Lithium manganese oxide is a traditional high specific capacity anode battery materialwhose theoretical specific capacity is as high as285mAh/g. The resource of manganesewhich is mainly included in manganese dioxide in the earth is abundant. The sufficientstorage ensures that lithium manganese oxide can be used as the energy supply of materialsin the future. In addition, manganese is a non-toxic element. So in the world thatenvironmental protection has been deeply rooted in the hearts of everyone, thecharacteristic guarantee its worth of exploiting it.However, it is still not realistic for lithium manganese oxide to be produced as anodematerial in large-scale. The mechanism of the circulation for charge and discharge, thereare still some problems which need to be studied deeply. The Mn3+is susceptible tooxidation in the process of preparation because of J-T effect. Layer structure is easy to turninto a spinel-structure in the discharge cycles, and Mn dissolved in the electrolyte. All thiseffect could reduce electrochemical properties.On the actual production, the high temperature solid phase method is the methodwhich is now commonly used, but this method cannot meet the requirements of the specificcapacity of lithium manganese oxide and cost of energy. The common method to solveabove problems is doping-ion and coating.In this paper, we set LiMnO2with doping-ion as the target, by changing the method ofpreparation, optimizing the process parameter, analyzing the structure and testing theelectrochemical properties.The main research contents and results are as follows:We obtain the LiMnO2with doping-ion through precursor by hydrothermal methodafter calcination. We adjust the parameter of calcination and hydrothermal method andoptimize them. According to the electrochemical performance, the result shows that the best process is the raw material is calcined at800℃for6h, then have reaction in the kettleat200℃for7d with the ratio of Li:Mn is20.We obtain the LiMnO2with doping-Cr through varying degree by hydrothermalmethod. We also prepare the LiMnO2with doping-Mg and doping-Mg by the same degree.The result shows that when the content of Cr is10%, we will get the best electrochemicalperformance, the first discharge capacity could reach153mAh/g, and after50cycles, it alsocould keep140mAh/g. Compare the LiMnO2with doping-Mg and doping-Mg, we learnthat LiMnO2with doping-Mg could improve property of discharge circulating, and LiMnO2with doping-Co was beneficial to the improvement of the discharge capacity.We prepare the LiMnO2with doping-Mg/Cr and doping-Co/Cr by the same degreeand compare electrochemical performance of them. The result shows that LiMnO2withdoping-Mg could improve property of discharge circulating, and LiMnO2with doping-Cowas beneficial to the improvement of the discharge capacity.