The Effect of Antisite Disorder and Particle Size on Li Intercalation Kinetics in Monoclinic LiMnBO3
The Effect of Antisite Disorder and Particle Size on Li Intercalation Kinetics in Monoclinic LiMnBO3
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DOI：
10.1002/aenm.201401916
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发表时间：
2015-04-22
影响因子：
27.8
通讯作者：
Ceder, Gerbrand
中科院分区：
文献类型：
--
作者：
Kim, Jae Chul;Seo, Dong-Hwa;Ceder, Gerbrand
在含有一维锂扩散通道的材料中，阳离子无序会强烈地影响锂的嵌入过程。这项工作提出了一个模型来解释单斜晶系LiMnBO_3的异常输运性质，扫描电子显微镜和同步辐射X射线衍射仪测定了这种材料含有较宽的粒度分布和Mn/Li反位无序。第一性原理计算表明，占据Li位的Mn阻碍了沿[001]方向的一维锂扩散通道。当通道被反位堵塞时，锂在大颗粒中的迁移率显著降低，而在小颗粒和颗粒表面的锂动力学对反位无序的存在不那么敏感。因此，在含有大颗粒分布的电极中，较小的颗粒具有较高的Li迁移率，并且通过恒电位间歇滴定测试所测得的Li扩散系数随颗粒大小而变化。单斜晶系LiMnBO_3的锂容量受反位无序大颗粒分数的动力学控制，但不受本质限制。这些结果有力地表明，纳米颗粒的大小将显著提高LiMnBO_3的电化学性能
In materials containing 1D lithium diffusion channels, cation disorder can strongly affect lithium intercalation processes. This work presents a model to explain the unusual transport properties of monoclinic LiMnBO3, a material determined by scanning electron microscopy and synchrotron X-ray diffraction to contain a wide particle size distribution and Mn/Li antisite disorder. First-principles calculations indicate that Mn occupying Li sites obstruct the 1D lithium diffusion channel along the [001] direction. While channel blockage by the antisites significantly lowers Li mobility in large particles, Li kinetics in small particles and particle surfaces are found to be less sensitive to the presence of antisite disorder. Thus, in an electrode containing a large particle size distribution, smaller particles have higher Li mobility, and the measured Li diffusivity as determined by potentiostatic intermittent titration test varies as a function of particle size. The Li capacity in monoclinic LiMnBO3 is kinetically controlled by the fraction of large particles with antisite disorder, but is not intrinsically limited. These results strongly suggest that particle nanosizing will significantly enhance the electrochemical performance of LiMnBO3