| In this thesis, high temperature solid-state method and wet chemical method were used to synthesize high voltage spinel cathode materials LiNixMn2-xO4 for lithium ion batteries, the affects of Ni amount on the structure and properties of the materials were investigated, the reaction mechanism of wet chemical method was deduced, and the product which had regular morphologies and excellent electrochemical properties were synthesized. Sol-gel method was also employed to synthesize adulterated materials LiNi0.5Mn1.5O4. In addition, the charge-discharge process of materials LiM0.5Mn1.5O4 was tested at 55℃to inspect if the electrolyte could stand high voltage at high temperature.Solutions presented in this thesis can be summarized as follows:- Solubility of Ni in LiNixMn2-xO4 is related to synthesis methods. Pure spinel materials LiNixMn2-xO4 (x≤0.5) can be synthesized by chemical wet methods such as carbonate sediment process and sol-gel method.- Synthesizing adulterated materials LiNi0.5Mn1.5O4 by chemical wet methods, the reaction temperature has much affects on the structure and properties of the product. The product which is synthesized at 800℃has the best electrochemical properties.- The properties of adulterated materials LiMxMn2-xO4 are related to adulterated element, among of them LiNixMn2-xO4 has the best electrochemical properties. The electrochemical properties increase with the increase of Ni amount.- Common electrolyte is unstable at high temperature, and it will decompose when charged to 4.95V at 55℃.- Electrochemical date for LiCr0.1Ni0.4Mn1.5O4 electrodes show tworeversible plateaus at 4.8V and 4.7V. the LiCr0.1Ni0.4Mn1.5O4 elecrode delivers a high intial capacity of 138mAh/g with excellent cycleability,. It's excellent capacity retention is largely attributed to structural stabilization which results from co-doping and increased theoretical capacity due to substitution of chromium.
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