| Lithium-enriched manganese-based cathode materials are considered as the most promising cathode materials for lithium ion batteries due to their cheap, environmentally bengin, high capacity and safety. However,the material must overcome some problems, such as the initial irreversible capacity and lower rate performance and so on. In this paper,the preparation process and surface coating of layered lithium-enriched0.5Li2MnO3·0.5LiNi1/3Co1/3Mn1/3O2, was investigated to improve its electrochemical properties.1. 0.5Li2MnO3·0.5LiNi1/3Co1/3Mn1/3O2 was prepared by using co-precipitation method, spray assisted co-precipitation method and microwave assisted co-precipitation method. The cathode material was characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM） and charge-discharge test. The results showed that the material sintered 10 h at 900 ℃ with lithium content in excess of 7% has a better crystal structure and excellent electrochemical performance. The material exhibits the first discharge capacity of 270.1 mAh/g at 20 mA/g in the range of 2.0-4.8V, and the charge discharge efficiency is 69.8%. The discharge capacity is 212.6 mAh/g in the 100 th cycle.2. Y2O3 coating of self-made lithium rich materials0.5Li2MnO3·0.5LiNi1/3Co1/3Mn1/3O2 of was investigated. The structure and electrochemical performance was studied by XRD, SEM, EIS and charge-discharge tests. The results showed that Y2O3 existed only on the surface, and had no effect on the crystal structure. The material coated with 1wt% Y2O3 exhibits higher discharge capacity and better cycle performance. Its capacity is 200.9 mAh/g at 200mA/g in the 100 th cycle,while the capacity of the pristine material is only 82.3 mAh/g. The data from EIS showed that Y2O3 coating decreased the impedance of the cathode material. |
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