锂离子电池正极材料LiNiO2的结构和性能

采用高温固相熔融加压法合成LiNiO2正极材料,研究了助熔剂LiNO3的加入量和反应体系中O2压力对材料的结构和放电容量的影响.结果表明,随着LiNO3加入量的增加,产物容量先增加后减小,LiOH和LiNO3摩尔比0.9:0.1时产物结构和容量性能最佳;增大反应体系中O2压力,产物结构和放电容量均得到改善.对LiNiO2进行循环性能检测,30次循环后放电容量保持率为81.8%,晶型保持很好,相变反应特征变得明显,但是充电平台电位降低.采用交流阻抗技术计算知Li 在LizNiO2活性材料中的扩散系数在10-9cm2s-1数量级,扩散系数较大,因而在充放电过程中Li 迁移扩散更容易,材料电化学活性提高.

Structure and properties of LiNiO2 as cathode material for Li-ion battery

LiNiO_2 cathod material was prepared through high-temperature solid-state melting pressuring method.The effects of LiNO_3 addition and O_2 pressure in reaction system on the structures and the discharge capacities of LiNiO_2 products were investigated.The results showed that with the increasing of LiNO_3 addition,discharge capacities of LiNiO_2 products increased at first and then decreased.When the molar ratio of LiOH and LiNO_3 is 0.9:0.1,the structure and discharge capacity are optimal.With the increasing of O_2 pressure,structure and discharge capacity of LiNiO_2 products were improved.Capacity conservation rate of LiNiO_2 after 30 cycles is 81.8%,structure is keeped very well,phase transformations are obvious,but the flat voltage in charge process decreased.Diffusion coefficients of Li~+ in Li_xNiO_2 calculated through AC method are at 10~(-9)cm~2s~(-1) order,they are upper,which indicates that the transfer and diffusion of Li~+ are easier during charge-discharge process,the electrochemical activity of material increases.