(1、北京有色金属研究总院, 北京 100088
2、北京科技大学固体电解质冶金测试技术国家专业实验室, 北京 100083)
摘 要: 用热重分析方法并配合中间产物及最终产物的物相鉴定,研究了LiCo1-xNixO2合成过程的机理及产物的结构和性能。碳酸锂和钴、镍的碱式碳酸盐,在共混后热合成LiCo1-xNixO2的过程分两步进行,第一步为碱式碳酸镍(钴)盐的热分解(<300 ℃),第二步 (>300 ℃)包括碳酸锂的分解和LiCo1-xNixO2的合成。温度升高,合成产物中锂含量增加,晶格参数增大,生成物为具有单相结构的LiCoO2和LiNiO2固溶体。随着LiCo1-xNixO2中 x 值的增加,晶格参数增大。合成过程中碳酸盐分解产生的CO对Co++、Ni++ 氧化成Co+++、Ni+++产生影响,因此合成的气氛和原料对产物有明显的影响。通过合成条件的优化得到的LiCo0.5Ni0.5O2和LiNiO2 放电量均可达到LiCoO2的水平。
关键字: LiCo1-xNixO2 合成机理 锂离子电池
(1.General Research Institute of Nonferrous Metals, Beijing 100088 ;
2.National Laboratory on Solid Electrolytes and Metallurgical Testing Techniques, University of Science and Technology Beijing, Beijing 100083)
Abstract:The mechanism of LiCo1-xNixO2(x=0~1) synthesis from Co and/or Ni carbonates and Lithium carbonate was investigated by thermogravimetric analysis. The products during the process were identified by X-ray diffraction. The results indicated that the process includes two steps. The first step is decomposition of Co and/or Ni carbonates(below 300 ℃), followed by Lithium carbonate decomposing and LiCo1-xNixO2 forming (300~900 ℃). LiCo1-xNixO2 is characterized by single phase and solid solution of LiCoO2 and LiNiO2. The cell volumes of LiCo1-xNixO2 crystals increase with x. Starting materials affect Ni+++ and/or Co+++ forming because of the CO reduction atmosphere produced during the carbonates decomposing. LiCo1-xNixO2(x≥0.5) can be synthesized by heating carbonates in air. LiNiO2 was only obtained from LiOH and Ni(OH)2 in oxygen. Through optimization of synthesis conditions were obtained LiCo0.5Ni0.5O2 and LiNiO2, which have better performances for cathode materials of Li-ion batteries than LiCoO2.
Key words: LiLiCo1-xNixO2 synthesis lithium-ion battery