Anisotropic Swelling and Fracture of Silicon Nanowires during Lithiation

作者：Xiao Hua Liu, He Gen Zheng, Li Sheng Zhong, Shan Huang, Khim Karki, Liqiang Zhang, Yang Liu, Akihiro Kushima, Wen Tao Liang, Jiangwei Wang, Jeong‐Hyun Cho, Eric S. Epstein, Shadi A. Dayeh, S. Tom Picraux, Ting Zhu, Ju Li, John P. Sullivan, John Cumings, Chunsheng Wang, Scott X. Mao, Zhi Zhen Ye, Sulin Zhang, Jian Yu Huang · 发表于：Nano Letters · 年份：2011 · DOI：10.1021/nl201684d · 被引用次数：815 · 研究领域：Advancements in Battery Materials、Semiconductor materials and devices、Semiconductor materials and interfaces

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 LiCoO(2) 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.