锂离子电池用活性正极材料LiCo_(1-x)Ni_xO_2

CATHODE MATERIALS OF LiCo 1-x Ni x O 2 FOR LITHIUM ION BATTERIES

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。

The mechanism of LiCo 1-x Ni x O 2( 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 LiCo 1-x Ni x O 2 forming (300～900 ℃). LiCo 1-x Ni x O 2 is characterized by single phase and solid solution of LiCoO 2 and LiNiO 2. The cell volumes of LiCo 1-x Ni x O 2 crystals increase with x. Starting materials affect Ni +++ and/or Co +++ forming because of the CO reduction atmosphere produced during the carbonates decomposing. LiCo 1-x Ni x O 2( x ≥0.5) can be synthesized by heating carbonates in air. LiNiO 2 was only obtained from LiOH and Ni(OH) 2 in oxygen. Through optimization of synthesis conditions were obtained LiCo 0.5 Ni 0.5 O 2 and LiNiO 2, which have better performances for cathode materials of Li ion batteries than LiCoO 2.