Layered Of Lini <sub> 1/3 </ Sub> Co <sub> 1/3 </ Sub> <sub> Of Mn 1/3 </ Sub> The O <sub> 2 </ Sub> Lithium-ion Battery Cathode Material Preparation And Characterization

Recently,Layered Li[Ni_(1-x)/2Co_xMn_(1-x)/2]O₂ is considered to be one of the best candidates to replace LiCoO₂.In this paper,Layered LiNi_1/3Co_1/3Mn_1/3O₂ was selected to be the object of our research and Layered LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized by the sol-gel method and ball-milling activation route.The studies of XRD,SEM,charge-discharge at constant current were introduced to characterize the structure, micro-morphology and electrochemical properties of the as-prepared materials.The lithium nickel cobalt manganese oxide LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized using citric acid as a chelating agent by a sol-gel method.It has good crystal structure,high theoretical capacity,well cycle performance.The effect of varying the acid to metal ion ratio R on the structural and electrochemical properties of the synthesized compound were studied.An acid to metal ion ratio R=0.8 got the best result.The effect of varying high temperature synthesizing conditions on the structural and electrochemical properties of the synthesized compound was studied.With Raising synthesizing temperature and prolonging sintering period appropriately,it could improve the crystallinity and the layered structure of the as-prepared materials.However,it also might result in the increase of particle size.The electrochemical test in 2.75-4.3V delivered the initial charge and discharge specific capacity of 191.3 and 163.8 mAh·g^-1 at a 0.1C rate,respectively,with the initial charge/discharge efficiency of 85.6%,and good cycling stability for layered LiNi_1/3Co_1/3Mn_1/3O₂ prepared in the optimized condition of acid to metal ion ratio R=0.8,and sintering for 8h at 950℃.LiNi_1/3Co_1/3Mn_1/3O₂ was prepared using different lithium raw materials.The results showed that LiNi_1/3Co_1/3Mn_1/3O₂ was prepared using lithium hydroxide as lithium raw materials with ammonia controlling the PH,which has high theoretical capacity,good cycle performance,but low tap density.The layered LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials with hexagonal structure were successfully synthesized by ball-milling activation followed with combustion method and high temperature sintering in air. The sample has a phase-pure hexagonalα-NaFeO₂ structure with a space group of R(?)m,and uniform particle size of 200-300nm.With ball-milling activation,uniform precursor with high reacting activity was obtained. The elemental stoichiometric coefficientφ_e of the specific formulas was calculated to ascertain the range of the acid to metal ion ratio K.The effect of varying the acid to metal ion ratio R on the structural and electrochemical properties of the synthesized compound were studied.An acid to metal ion ratio K=0.7 got the best result.The pretreatment temperature process was investigated.The electrochemical test in 2.75-4.3V delivered the initial charge and discharge specific capacity of 184.3 and 156.7 mAh·g^-1 at a 0.1C rate,respectively,with the initial charge/discharge efficiency of 85.0%,and the discapacity of 150.8mAh·g^-1 on the 30^th cycle at a 0.5C rate for layered LiNi_1/3Co_1/3Mn_1/3O₂ prepared in the condition of sintering for 10h at 950℃.LiNi_1/3Co_1/3Mn_1/3O₂ was prepared using lithium carbonate,lithium hydroxide,lithium nitrate as raw materials respectively.The results showed that LiNi_1/3Co_1/3Mn_1/3O₂ that prepared using lithium nitrate as lithium raw materials has good structural and electrochemical properties.