锂离子电池正极材料LiNixCo1 - xO2局域结构的研究

对合成制备的LiNixCo1 - xO2正极材料及其稀土金属Ce元素添加改性的正极材料进行了X射线衍射(XRD)和扩展X射线吸收精细结构(EXAFS)表征.结果表明,随着焙烧温度的升高,物相组成趋于单一,晶格趋向完整,800 ℃时完全形成LiNiO2、LiCoO2晶相结构.LiNixCo1 - xO2样品中Ni/Co摩尔比不影响LiNiO2晶相的形成,而只影响其晶相组成;掺杂的稀土金属Ce元素以CeO2状态存在于产物中,CeO2对LiNiO2晶相形成有一定的影响;LiCoO2的焙烧温度不能大于900 ℃,否则Co被氧化为Co3O4;样品中Ni与Co原子的局域结构,除Ni与Co原子相互影响外,掺杂Ce后对它们的局域结构也有较大影响.

EXAFS study of LiNixCo1 - xO2 cathode materials

Ce element modified LiNi_xCo_1-xO₂ cathode materials were prepared by precipitation from nickel acetate , cobalt acetate , lithium acetate , cerous chloride and NH₃·HO₂ . The resulted materials were characterized by X-ray diffraction and Ni K-edge and Co K^_-edge Extended X-ray Absorption Fine Structure (EXAFS) spectra.The results show that the crystallite phases of the synthesized cathode materials tend gradually to simplicity and integrity with increasing the calcining temperature , pure LiNiO₂ and LiCoO₂ phase are formed at calcining temperature 800 ℃ in air , and Co element in the LiCoO₂ phase is however oxidized and forms Co₃O₄ phase at temperature over 900 ℃. The additional Ce element in the sample exits only CeO₂ , and more effected on the Ni atom and Co atom local structure is indicated by EXAFS spectra.