A continuum model of deformation, transport and irreversible changes in atomic structure in amorphous lithium–silicon electrodes
A continuum model of deformation, transport and irreversible changes in atomic structure in amorphous lithium–silicon electrodes
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DOI：
10.1016/j.actamat.2015.07.036
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发表时间：
2015-10
期刊：
影响因子：
9.4
通讯作者：
A. Bower;E. Chason;P. Guduru;B. Sheldon
中科院分区：
文献类型：
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作者：
A. Bower;E. Chason;P. Guduru;B. Sheldon
最近的实验和原子尺度计算表明，受应力固体中扩散的标准连续模型不能准确描述锂硅合金中的输运、变形和应力。我们认为，这是因为经典模型不考虑已知在充放电循环期间发生的Si原子结构的不可逆变化。一个更一般的模型中的非晶固体的扩散进行了描述，它允许未被占用的Si晶格的网站被创建或破坏。这可能作为热激活过程发生;或作为应力下不可逆塑性变形的结果。该模型预测了实验中观察到的一系列现象，这些现象无法使用经典模型捕获，包括由充放电循环引起的体积的不可逆变化，拉伸和压缩屈服应力之间的不对称性，以及在许多充放电循环中机械和电化学响应的缓慢演变。
Recent experiments and atomic scale computations indicate that the standard continuum models of diffusion in stressed solids do not accurately describe transport, deformation and stress in Li–Si alloys. We suggest that this is because classical models do not account for the irreversible changes in atomic structure of Si that are known to occur during a charge–discharge cycle. A more general model of diffusion in an amorphous solid is described, which permits unoccupied Si lattice sites to be created or destroyed. This may occur as a thermally activated process; or as a result of irreversible plastic deformation under stress. The model predicts a range of phenomena observed in experiment that cannot be captured using classical models, including irreversible changes in volume resulting from a charge–discharge cycle, asymmetry between the tensile and compressive yield stress, and a slow evolution in mechanical and electrochemical response over many charge–discharge cycles.