【作者】 张爱珍；

【导师】 杨长春；

【作者基本信息】 郑州大学 ， 物理化学， 2006， 硕士

【摘要】 锂离子二次电池是一种性能优良的化学电源，正极材料性能的改善和提高对其近年来的快速发展起到了关键作用。目前，具有α-NaFeO₂型层状结构的LiCoO₂已经在商品化的小型锂离子电池中广泛使用，LiCoO₂的循环性及倍率放电性能好，但除钴的资源和价格制约因素外，其过充不安全性限制了它在大容量电池的应用。层状LiNiO₂化合物价格低、比容量高、对环境友好，被认为是有希望的正极材料，但它合成困难，结构不稳定又导致循环过程的容量衰减，这阻碍了它的实际应用。采用多元素掺杂形成多元固溶体，以提高其结构稳定性和改善其电化学性能，是该材料领域一个普遍使用的方法。 本论文主要研究用作锂离子电池正极材料的层状锂镍钴基氧化物LiNi_0.8-xCo_0.2Al_xO₂和锂镍锰基氧化物LiNi_0.5Mn_0.5O₂和LiNi_1／3Co_1／3Mn_1／3O₂的制备工艺、及工艺参数对产物性能的影响。 1．锂镍钴基氧化物的研究 对比了不同方法和不同镍源时合成LiNi_0.8-xCo_0.2Al_xO₂的工艺，用X-射线衍射、热重、循环伏安和模拟电池的充放电对所得样品的结构、热稳定性和电化学性能进行了测试。结果表明： 1．1 三价镍源和锂源化合物通过低温固相法在空气中培烧不能得到LiNiO₂，原材料中加入钴后，能在空气中合成具有LiNiO₂结构的化合物LiNi_0.8Co_0.2O₂。同时加入钴、铝，在空气中比较容易合成具有LiNiO₂结构的化合物LiNi_0.7Co_0.2Al_0.1O₂。制备LiNi_0.7Co_0.2Al_0.1O₂时，用两阶段的烧结方式较好（第一阶段600℃6h，第二阶段750℃10h）。溶胶凝胶法得到的LiNi_0.7Co_0.2Al_0.1O₂，分散程度高，颗粒之间发生团聚少。 1．2 用不同镍源在空气中经两阶段烧结后均能得到结晶良好，具有六方层状结构的LiNi_0.7Co_0.2Al_0.1O₂化合物。第一阶段烧结条件相同，第二阶段烧结所需温度依β-NiOOH，Ni₂O₃，Ni（OH）₂顺序为700、750、800℃。用三价镍源制得的材料晶胞体积小于亚镍，R值高于亚镍，材料的结晶更好，层状结构更明显。 1．3 铝的添加可使产物的热稳定性得到提高，添加10％铝可使材料的热分解温度提高55℃。更多还原

【Abstract】 Lithium ion secondary battery is an excellent chemical power supply. Its rapid development in last decades was mainly attributed to the improvement and progress of cathode material. Up till now, LiCoO₂ served as cathode material, with layer structure like α-NaFeO₂, has being already extensively used in small sized commercial lithium ion battery. Although the cyclic property, and discharge capacity at multiple ratio current were good for LiCoO₂, but the insecurity under over charge condition restrict its application in large sized lithium batteries, except of the limiting factors of resources and prize related with cobalt. LiNiO₂ with layer structure was believed to be an attractive potential cathode material, due to its low prize, high specific capacity and environment benign. But it is difficult to produce stoichiometric LiNiO₂ with pure phase, and its crystal structure is instable during charge-discharge cycle that leading to the loss of capacity gradually, all these obstruct the practical application of LiNiO₂. In order to modify the crystal structure stability of LiNiO₂ and improve its electrochemical property, an useful method commonly used in the field of researching LiNiO₂ based cathode material was partially substituting the Ni atom in LiNiO₂ by variety elements to form solid solution of multi-components.The main point of this thesis was to investigate the technology for preparing the cathode material with layer structure for lithium ion battery, such as LiNi_0.8-xCo_0.2Al_xO₂ based on LiNi_xCo_1-xO₂ and LiNi_1/3Co_1/3Mn_1/3O₂ based on LiNi_0.5Mn_0.5O₂, and to study the relation between the technique parameters and the performance feature of the yields.1. Research on the material based on LiNi_xCo_1-xO₂Different methods for preparing LiNi_0.8-xCo_0.2Al_xO₂ and the performance feature of the target products were compared, from the views of crystal structure, thermal stability and electrochemical property, by means of X-ray diffraction （XRD）, thermal gravimetric analysis （TGA）, cyclic voltammogram （CVA） and charge-discharge of simulated cell. The results are showed as follow.1.1 LiNiO₂ can’t be prepared by a low temperature solid state reaction from trivalence nickelates and lithium hydroxide. When Co is doped, LiNi_0.8Co_0.2O₂ , with LiNiO₂ structure, is synthesized in air. When Co and Al are doped at the same time, LiNi_0.7Co_0.2Al_0.1O₂ with LiNiO₂ structure is easily received by two-step calcination in air （the 1 st step:600℃ 6h;the 2nd step: 750℃10h）. LiNi_0.7Co_0.2Al_0.1O₂ synthesized by sol-gel method has large particle size and small agglomerates.1.2 LiNi_0.7Co_0.2Al_0.1O₂ with well-ordered hexagonal structure is synthesized by two-step calcination in air from different nickel resources. With the same 1 st step calcination condition, the 2 nd step calcination temperature is 700,750 and 800℃ for β -NiOOH, Ni₂O₃ and Ni（OH）₂ respectively . In addition, the cell volumes fortrivalence nicklates resources are smaller than that for Ni（OH）₂, and I_（003）/I_（104） is larger than that for Ni（OH）₂. All indicates that LiNi_0.7Co_0.2Al_0.1O₂ from trivalence nickelates resources has a better crystal and better layered structure.更多还原