The Synthesis Of Lithium Ion Battery Anode Materials For Lithium Manganese Phosphate And Performance Research

LiFeP04has been demonstrated to be one of the most promising cathode materials for lithium-ion batteries, especially for large-scale applications, such as plug-in hybrid vehicles and stationary powers, because of the inherent low cost, nontoxicity, and extremely high stability. However, the specific energy of LiFePO4is still lower compared with the conventional LIB(Lithium-ion battery) using LiCoO2and LiMN2O4because of the low relative redox voltage of3.5V versus Li/Li+LiMnPO4is a much more promising cathode material for lithium-ion batteries than LiFePO4because of its higher redox voltage of4.2V versus Li/Li+. Therefore, a lot of research and papers began to appear in recent years. However, most people just develop a new synthesis method. There is few papers focus on the deeper and systematic research of LiMnPO4. The main contents of this thesis are followed:1、The pure phase lithium manganese phosphate was prepared by different synthesis methods:the precipitation method; the template method; the MnP04precursor method and the solid-state method. The characterization and electrochemical properties of there methods were extensively studied. Finally, we find the solid-state method is the best method to synthesis the lithium manganese phosphate. The as-prepared LiMnP04gives a capacity of102mAhg-1at0.1C.2、 LiFe0.2Mn0.8PO4was prepared by a solid state reaction process in combination with a ball-milling with carbon black and sucrose as carbon sources. The effects of the ratio of carbon precursors, the total carbon content, and ball-milling time on the physico-chemical and electrochemical properties of C-LiFeo2Mn0.8PO4are extensively studied. Under the optimal condition, the as-prepared LiFe0.2Mn0.8PO4gives a capacity of150mAhg-1at1/20C and110mAhg-1at1C. A novel lithium-ion battery consisting of LiFeo.2Mn0.8PO4cathode, Li4Ti5O12anode delivers a capacity of70mAhg-1and a specific energy of170Whkg-1with an output voltage of2.45V based on the total weight of both active electrode materials. The cell also exhibits an excellent cycling stability with a capacity retention of92%over200charge/discharge cycles.3. LiMnPO4and LiMno.9M0.1PO4(M=Mg, Fe, Ni, Zn, Co) was prepared by a solid state reaction process in combination with a ball-milling with carbon. The reaction temperature and heat of these materials are tested by DSC of the condition with and without electrolyte. The results show that the thermal stability of lithium manganese phosphate can be improved obviously through the Zn doping.