锂离子电池LiNiO_2正极材料的高温固相合成①及其影响因素研究

采用高温固相法合成了LiNiO2,XRD确定了合成物的结构,用SEM表征LiNiO2粉体的形貌.探讨了反应条件:包括原材料、Li/Ni摩尔比、烧结气氛和温度对产物结构和性能的影响,从而优化了LiNiO2的合成工艺.在空气中合成只能得到Li2Ni8O10相,在O2中才能得到LiNiO2相,所得LiNiO2的电化学性能明显优于所得Li2Ni8O10.合成电化学性能良好的LiNiO2需要稍过量的锂和在氧气中600℃恒温3h,720℃恒温6h,合成过程中得预热处理,解决了低温下反应速度慢,高温下易于烧结而难于控制产物粒径的问题.分析了采用固相配位法合成LiNiO2失败的原因.

Study of LiNiO_2 synthesized by the high temperature solid state reaction and the influences of preparation conditions

LiNiO_2 was synthesized by the high temperature solid state reaction. The structure was determined by XRD and the appearance of LiNiO_2 power was characterized by SEM. The influences of preparation conditions such as raw materials, the mole ratio of Li/Ni, the sintering atmosphere and the sintering temperature on the structure and electrochemical performance of the product were discussed. The synthetic technology was optimized. In air Li_2Ni_8O_(10) phase can be synthesized, but LiNiO_2 can be obtained only in O_2, the electrochemical performance of LiNiO_2 is evidently better than that of Li_2Ni_8O_(10). For synthesizing LiNiO_2 of good electrochemical performance, a little excess of lithium, keeping temperature at 600℃ for 3 h and 700℃ for 8 h are necessary. At the temperature, the reaction rate is slow, at high temperature, it is difficult to control the particle size of the product. The preheating step in the synthesis solves this problem. The failure to synthesis LiNiO_2 by solid state coordination method was analyzed.