Study On Synthesis And Low Temperature Preperties Of Ternary Cathode Materials LiNi_1/3Co_1/3Mn_1/3O₂

With the rapid development of our society and economy, the demand for new battery materials is increasing. Own to its safety, low cost, high specific capacity（277mAh/g） and high ability of lithium ion diffusion, ternary anode material LiNi_1/3Co_1/3Mn_1/3O₂ for lithium-ion secondary battery is considered to be a better than LiCo O2 anode material, so it has a good application prospect. Excellent performance LiNi_1/3Co_1/3Mn_1/3O₂ anode material was prepared via coprecipitation method, the morphology of the materials, the microstructure characterize, electrochemical performance of lithium storage and low temperature performance were studied by XRD, SEM and constant current charge and discharge technologies. The experimental results are as follows:1、We prepared LiNi_1/3Co_1/3Mn_1/3O₂ anode material under different aging time, then their electrochemical performance at room temperature was studied by charging and discharging at 0.1C with a voltage between 2.75-4.6 V. The results show that aging time has a great influence on the electrochemical properties of these materials. The aging time of 48 h has optimal electrochemical properties, its first charge and discharge capacity is 205/171.6mAh/g, for the first time the coulomb efficiency is 83.7%, even after 50 times cycle the discharge capacity is also as high as 143.7mAh/g, capacity retention rate is 83.7%, shows that it has a perfect cycle performance.2、Ball mill ternary precursor materials which were prepared by different aging time and Li2CO3, then studied its electrochemical performance respectively at room temperature. Charging and discharging at 0.1C with a voltage between 2.75-4.6 V. The results show that the ternary material electrochemical properties is different as ball milling time increases, ternary material with ball mill time of 4h has a better electrochemical performance and higher mixing degree.3、After studied the ternary materials’ electrochemical properties at room temperature, we selected the ternary material of aging time of 48 h and ball mill time of 2 h, 4 h, 6 h for low temperature performance studying, we selected the temperature of 0℃ and-25℃, we find that ternary material with ball mill time of 4 h still has the best electrochemical properties. Under 0℃ and-25℃, the first charging and discharging capacity is 208.6/156.8mAh/g and 194.2/126.9mAh/g respectively, coulomb efficiency is 75.2% and 65.3%. Li+ movement and conduction ability significantly diminished at lower temperatures, thus the materials’ electrochemical performance are declined. But the electrochemical performance is still stable at low temperatures, after 20 cycles, the discharging capacity is 126.2mAh/g and 113.5mAh/g. capacity retention rate is 80.5% and 89.5%, The capacity attenuates severely at 0.5C under the low temperature.