Anisotropic Swelling and Fracture of Silicon Nanowires during Lithiation
Anisotropic Swelling and Fracture of Silicon Nanowires during Lithiation
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DOI：
10.1021/nl201684d
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发表时间：
2011-08-01
期刊：
影响因子：
10.8
通讯作者：
Huang, Jian Yu
中科院分区：
文献类型：
--
作者：
Liu, Xiao Hua;Zheng, He;Huang, Jian Yu
我们报告了直接观察到硅纳米线在固体电解质与锂反电极或液体电解质与LiCoO2反电极的锂化过程中意外的各向异性膨胀。这种各向异性膨胀归因于在锂化反应前沿容纳大体积应变的界面过程，该过程敏感地依赖于晶体取向。这种各向异性膨胀导致锂化硅纳米线具有显著的哑铃形横截面，这是由于塑性流动和随后由锂化壳中拉伸环向应力积累引起的颈部不稳定而形成的。塑性驱动的形态不稳定性经常导致锂化纳米线断裂，现在被视频捕获。这些结果为电池退化机制提供了重要的见解。
We report direct observation of an unexpected anisotropic swelling of Si nanowires during lithiation against either a solid electrolyte with a lithium counter-electrode or a liquid electrolyte with a LiCoO2 counter-electrode. Such anisotropic expansion is attributed to the interfacial processes of accommodating large volumetric strains at the lithiation reaction front that depend sensitively on the crystallographic orientation. This anisotropic swelling results in lithiated Si nanowires with a remarkable dumbbell-shaped cross section, which develops due to plastic flow and an ensuing necking instability that is induced by the tensile hoop stress buildup in the lithiated shell. The plasticity-driven morphological instabilities often lead to fracture in lithiated nanowires, now captured in video. These results provide important insight into the battery degradation mechanisms.