| LiNi0.8Co0.15Al0.05O2 is one of the most commercially valuable high nickel materials. It has many advantages, such as high capacity, low price, nontoxic LiNO2 But the synthesis of LiNO2 is difficult, however, mixing Co and Al can improve the synthetic difficult problem and can reduce mixed cations. In order to get the better performance of LiNi0.8Co0.15Al0.05O2, for example, cycle stability makes the irreversible capacity loss less, having high capacity and so on. A lot of research scholars have done more research work.In this paper, we get Ni0.8Co0.15Al0.05(OH)2 precursor by coprecipitation. In order to get higher NCA sphericity, the synthesis process of precursor were studied. Because of the addition of aluminium salts in the NCA, synthetic materials are difficult, the spherical degree is not high, the relatively small particles, so change the way with aluminium salt and alumina sol, to the preparation of precursor.For reducing the lithium nickel mixed materials, the sintering process of materials (different high temperature sintering temperature and sintering atmosphere) were studied.The samples are described of by SEM, XRD, laser granularity, XPS, ICP and electrochemical test. Through the coprecipitation method in the traditional way, we prepare the LiNi0.8Co0.15Al0.05O2 material. The analysis results show that cation mixed of material gradually reduce with the increase of residence time and the reaction time, in the same time, the crystallinity and the order ate getting better and better. When the remain time is 18 h, the lithium nickel of material is less, and the grain size of mixed samples is evener.First discharge capacity gets the highest value of 170.7 mA·h/g. Meanwhile, the discharge efficiency is best, and the first time reached 87.3%. After 30 cycles, capacity retention rate of the sample is 91%.When the reaction time is 168 h, the sample of cation mixed is minimum and article size distribution is uniform, and the first time discharge capacity is the largest 178.6 mA·h/g. The first time discharge efficiency is 86.7%. After 30 cycles, the capacity retention rate is 90.4%. In conclusion, preparing precursor by coprecipitation the best residence time is 18 h, and the best reaction time is 168 h in the reaction kettle.The particles of LiNi0.8Co0.15Al0.05O2 are larger and uniformity by joining colloid and they are almost 10μm. After reacting 120 h, the crystallinity of the sample is uniformity and the order is good. The particles are larger and fewer cations are mixed, and the first discharge capacity is 180.7 mA·h/g. After circling 30 times, maintain the capacity of a rate gets 93.9%.By studing the high temperature sintering process of the sample, we can know that: when the high temperature sintering temperature is 720℃ and the whole process of sintering atmosphere oxygen is under 0.1 MPa, the samples have good sphericity and uniform particles. The content of Ni3+ is most, and the content of Ni2+ is least. The results represent that the amount of cationic mixed is least.First discharge capacity is 177.9 mA·h/g and the capacity of the attenuation rate is minimal, as low as 0.34%. After 30 times, the circulating rate of the sample is 91%.
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