Prepare And Study Of The Performance Of Lithium-nickel-cobalt-manganese Oxides Cathode Material For Lithium-ion Batteries

The lithium- nickel -cobalt- manganese oxides cathode as the cathode materials for lithium ion battery offer the advantages of higher capacities of discharge and excellent cycle life and higher tap density etal.LiNi1/3Mn1/3Co1/3O2 has become attractive as an alternative cathode material for LiCoO2.The Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is considered as the next promising cathode used in lithium ion battery for electric vehicles.In this paper,we have systematically studied LiNi1/3Mn1/3Co1/3O2 and Li[Li0.2Mn0.54Ni0.13Co0.13]O2 separately using ultrafine grinding - spray drying method and carbonate co-precipitation method.The precursor of LiNi1/3Co1/3Mn1/3O2 was obtained by ultrafine grinding-spray drying method with spherical Ni(OH)2, Co3O4, Mn3O4 as the raw materials.The effect of synthesizing conditions such as lithium source,calcination temperature etal on the characteristics of LiNi1/3Co1/3Mn1/3O2 have been studied.The optimal technological conditions for prepared LiNi1/3Co1/3Mn1/3O2 were the precursor mixed with excessive 5% lithium hydroxide monohydrate sintered at 500℃for 3h then sintered at 900℃for 12h after Mechanical ball mill.It showed an initial discharge capacity of 164.4mAh/g at 0.1 C rate between 2.8 and 4.3 V,and its capacity retention was 99% after 30 cycles.The discharge capacity at 2C rate was 142.3Ah/g. It showed an initial discharge capacity of 167.8mAh/g at 0.1C rate at 55℃,and its capacity retention was 98.9% after 10 cycles.The capacity at 2C rate was 150.7Ah/g.When the voltage of charge increases to 4.4V,4.5V,4.6V,the discharge capacity were respectively 168.9mAh/g,183.7mAh/g,195mAh/g at 0.1 C rate at room temperature with excellent cycle life.The precursor of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 has been synthesized by a carbonate co-precipitation method. The effect of the pH value, the feeding mode etal on the characteristics of precursor and the electrochemical properties of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material were separately inspected.The well-distributed spherical precursor with about 10μm can get at 50℃for 10h with the pH value was fixed to 9.0, and the stirring speed of the mixture was fixed to 600r/min in the three-phase parallel feeding mode.Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material prepared from the precursor showed an initial discharge capacity of 252.4 mAh/g at 0.1C rate between 2 and 4.8 V,and its capacity retention was 99% after 20 cycles. The discharge capacity at 0.2C rate, 0.5C rate,1C rate,were respectively 229.3mAh/g,199.6mAh/g, 172.8mAh/g. Li[Li0.2Mn0.54Ni0.13Co0.13]O2 showed an initial discharge capacity of 285.1mAh/g at 0.1C rate between 2 and 4.8 V at 55℃, and its capacity retention was 97% after 20 cycles,. the efficiency of the first charge and discharge was increased 69.9% to 84.3% after it was treated with HNO3 of 0.2mol/L for 2h.