Characterization of Li1+yNixCo1−2xMnxO2 positive active materials for lithium ion batteries
Characterization of Li1+yNixCo1−2xMnxO2 positive active materials for lithium ion batteries
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DOI：
10.1016/j.jpowsour.2005.03.046
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发表时间：
2005-08
影响因子：
9.2
通讯作者：
K. Shizuka;Takako Kobayashi;K. Okahara;K. Okamoto;Sho Kanzaki;R. Kanno
中科院分区：
文献类型：
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作者：
K. Shizuka;Takako Kobayashi;K. Okahara;K. Okamoto;Sho Kanzaki;R. Kanno
采用固相反应法制备了层状Li1+yNixCo1−2xMnxO2材料，并用多种方法进行了表征。电池的性能取决于组成。随着Co含量(1−2x)的降低，材料的倍率性能变差。另一方面，随着过量Li含量(Y)的增加，其性能也有所改善。与组成变化相关的电池性能的变化与结构无序(阳离子混合)和电导率(体积电阻率)密切相关。阳离子的混合程度很大程度上取决于Co含量(1−2x)。另一方面，体电阻率很大程度上依赖于过量Li含量(Y)。换言之，通过降低阳离子混合和体积电阻率，电池的性能得到了改善。随着Co含量(1−2x)或过量Li含量(Y)的增加，只有Ni的K边X射线吸收近边结构(XANES)谱显示出由于Ni的氧化而向高能方向移动。晶胞尺寸随Co含量(1−2x)或过量Li含量(Y)的增加而减小。它们可能是由于从Ni2+(RNI=0.69？)变为较小的Ni3+([公式：请参阅文本]？)所致。从这些结果推测，体电阻率的降低与Li1+yNixCo1−2xMnxO2中Ni3+浓度的增加密切相关。
Layered Li1+yNixCo1−2xMnxO2materials were prepared by a solid-state reaction at 950°C for 10h in air and characterized by various methods. The cell performance depended on the composition. The rate performance deteriorated as Co content (1−2x) decreased. On the other hand, it improved as excess Li content (y) increased. The change of cell performance associated with composition variations was closely related to both the structural disorder (cation mixing) and the electrical conductivity (volume resistivity). The degree of cation mixing depended greatly on Co content (1−2x). On the other hand, the volume resistivity depended greatly on excess Li content (y). In other words, the cell performance was improved by the reduction of cation mixing and volume resistivity. Only Ni K-edge X-ray absorption near edge structure (XANES) spectra showed edge shifts to higher energy due to the oxidation of Ni as either Co content (1−2x) or excess Li content (y) increased. The unit cell size decreased as either Co content (1−2x) or excess Li content (y) increased. They are probably caused by the change from Ni2+(rNi=0.69Å) to the smaller Ni3+( [Formula: see text] Å). From these results, it is assumed that the reduction of volume resistibity is closely related to the increase of Ni3+concentration in Li1+yNixCo1−2xMnxO2.