Synthesis And Al-doping Modification Of LiNi_1/3Co_1/3Mn_1/3O₂Cathode Material

material has been considered as one of the most promising cathode materials for rechargeable lithium ion battery due to its lower cost, higher specific capacity, milder thermal stability and no harm to environment. In this paper, the layered LiNi1/3Co1/3Mn1/3O2material was synthesized by high temperature calcination based on the precursor Ni1/3Co1/3Mn1/3(OH)2prepared by hydroxide coprecipitation method. And the technological parameters of the synthetic process were investigated and optimized. In order to improve the cycle and rate performance of LiNi1/3Co1/3Mn1/3O2material, the Al-doping modification was conducted under the optimum condition. The obtained cathode materials were characterized by Particle Size Distribution, Tap-density, SEM, EDS, ICP, XRD and electrochemical properties.The effects of synthesizing technological parameters on the performance of LiNi1/3Co1/3Mn1/3O2material were investigated. And the optimum conditions were obtained as the pH value was11.0, the ammonia concentration was0.50mol·L-1, reaction time was24h, calcination temperature was950℃, calcination time was10h and the molar ratio of Li/(Ni+Co+Mn) was1.05. The results showed that the morphology outline of LiNi1/3Co1/3Mn1/3O2material was evident; the material presented layered α-NaFeO2structure and the cationic mixing was low; the initial discharge specific capacity was144.5mAh·g-1at the rate of0.2C and the voltage range of2.7-4.2V, the capacity retention ratio was81.5%after50cycles.The effects of Al-doping modification on the performance of LiNi1/3Co1/3Mn1/3O2material were carried out. The results showed that small doping of Al element had no effect on the particle size, tap-density and morphology of the material. XRD results indicated that Al-doping did not change the layered α-NaFeO2structure of the material with good crystallization and pure phase. When doping quantity was0.02, the capacity retention ratio of the modified material was95.7%after50cycles, which was higher than that of the bared one (81.5%) at the rate of0.2C and the voltage range of2.7-4.2V; Meanwhile, the rate performance was greatly improved by keeping capacity of100.1%,99.9%,99.5%,97.9%and96.4%after6cycles respectively, compared with96.4%,96.8%,98.6%,96.4%.94.7%of the bared one at the rate of0.1C,0.2C,0.5C,1C and2C.