熔融盐法合成球形锂离子电池正极材料LiNi_(0.8)Co_(0.2)O_2

采用热分析法对不同组成的LiOH-LiNO3二元体系进行研究,绘制了具有最低共熔点的该二元体系T-x相图,该体系的最低共熔点为175.7℃.利用低共熔混合物LiNO3-LiOH为锂盐,与前驱体球形Ni0.8Co0.2(OH)2混合烧结制备出了球形锂离子电池正极材料LiNi0.8Co0.2O2.探讨了Li/(Ni+Co)摩尔比、合成温度、合成时间等因素对产品的影响.X射线衍射分析表明合成的材料具有规整的层状NaFeO2结构,SEM表明所得材料为球形.充放电测试表明在3.0~4.3的电压范围内,首次放电比容量可达170 mAh.g-1,充放电效率为95.5%.结果表明采用该工艺可以制备出电化学性能良好的LiNi0.8Co0.2O2正极材料.

Preparation of Spherical LiNi0.8Co0.2O2 as Cathode Material for Lithium ion Battery by a Molten Salt Method

The thermal properties of LiOH-LiNO3 mixture have been studied.The T-X phase diagram of the eutectic mixture shows that the binary is a simple eutectic system with a lowest melting point of 175.7 ℃.Spherical LiNi0.8Co0.2O2 for lithium ion battery is prepared by using molten salt LiOH-LiNO3 with spherical precursor Ni0.8Co0.2(OH)2.The influences of preparation conditions such as the mole ratio of Li/(Ni+Co),the sintering temperature and the reaction time of the product are discussed.The XRD results indicate that the material LiNi0.8Co0.2O2 shares a similar ordered layer structure as NaFeO2 does.SEM photographs show the powders are pherical dispersed particulate.Charge-discharge tests show that LiNi0.8Co0.2O2 cathode prepared by a molten salt method has an initial discharge capacity as high as170mAh/g and excellent capacity retention in the range3.0~4.3 V,the efficiency of coulomb is 95.5%.It is suggested that the cathode material LiNi0.8Co0.2O2 with good electrochemical property can be prepared by this technology.