Investigation And Preparation Of Compound Active Cathode Material For Lithium Ion Battery

In this paper, co-precipitation method has been used to synthesize the material.Preparation and properties(structure, shape, density and electrochemical performance) are systematically explored. The effect of the precursor on the properties and performance are investigated. And we have brought forward the idea of emphasizing on the study of the precursor.In this study, Li[Ni_1/2Mn_1/2]O₂ powers are prepared by co-precipitation method with ammonia as a chelating agent.The relation between the performance and type of pH, lithium resources, calcining condition and cooling pattern have been investigated.The results prove that the sample of Li[Ni_1/2Mn_1/2]O₂ which are sintered for 9h at 800℃ from pH= 11.0, LiOH as Li resource, cooled in the stove are best. The particles are uniform and in the size rang of 2³Î¼m. And the tap density is 1.8g/cm³. Li[Ni_1/2Mn_1/2]O₂ powers exhibit 10th-discharge capacity of 133mAh/g in the voltage range of 2.8⁴.3V and at a specific current of 10mA/g.Li[Ni_(1-x)/22Co_xMn_(1-x)/2]O₂(01/2Mn_1/2]O₂.The structure and electrochemical properties have been investigated. All the compounds have a-NaFeO₂ type structure with a space group R3m.The samples with x= 1/3, 0.2 have better performance, and the influence of the synthesizing condition, structure and shape on the samples are discussed. By the use of the thermal analysis, XRD, SEM and electrochemical measurement, the structure and performance of the sample are studied, and the synthesis process is optimized by comparing structure and performance with one another.The results indicate that the process conditions including synthesis atmosphere, pH value, concentration of ammonia, LiOH/M(OH)₂ molar ratio, quenching pattern, calcining temperture, calcining time are important for the preparation of the samples. Li[Ni_1/3Co_1/3Mn_1/3]O₂ powers prepared by the best synthesis technics exhibit discharge capacity of 156.2mAh/g after 10 cycles.The particles are about 5μm, and tap density is 2.0g/cm³. Electrochemical measurements show that LiNi_0.4Co_0.2Mn_0.4O₂ has about discharge specific capacity of 150mAh/g after 17 cycles, which would be a potential cathode.