Tokranov Anton, Sheldon Brian W, Li Chunzeng, Minne Stephen, Xiao Xingcheng
Brown University - School of Engineering , 182 Hope Street, Box D, Providence, Rhode Island 02912, United States.
ACS Appl Mater Interfaces. 2014 May 14;6(9):6672-86. doi: 10.1021/am500363t. Epub 2014 Apr 16.
Precise in situ atomic force microscopy (AFM) is used to monitor the formation of the solid electrolyte interphase (SEI) on Si electrodes. The stability of these passivation films on negative electrodes is critically important in rechargeable Li-ion batteries, and high capacity materials such as Si present substantial challenges because of the large volume changes that occur with Li insertion and removal. The results reported here show that the initial rapid SEI formation can be stabilized before significant Li insertion into the Si begins and that the rate at which this occurs varies significantly with the nature of the surface. The initial cycling conditions also have a substantial impact on the SEI that forms, with faster rates leading to a smoother, thinner SEI film. To quantitatively interpret the SEI measurements, irreversible expansion of the Si during the first cycle was also monitored in situ with specifically designed specimen configurations. On the basis of the experimental results, relatively simple models were also used to describe the initial formation and stabilization of the SEI and to describe the relationship between the SEI thickness and expected SEI degradation mechanisms.
精确原位原子力显微镜（AFM）用于监测硅电极上固体电解质界面（SEI）的形成。这些负极上钝化膜的稳定性在可充电锂离子电池中至关重要，而诸如硅之类的高容量材料由于锂嵌入和脱出时发生的巨大体积变化而带来了重大挑战。此处报道的结果表明，在锂大量插入硅之前，初始快速形成的SEI可以得到稳定，并且其发生速率会因表面性质的不同而有显著差异。初始循环条件对形成的SEI也有重大影响，较快的速率会导致形成更光滑、更薄的SEI膜。为了定量解释SEI测量结果，还使用专门设计的样品配置原位监测了硅在第一个循环中的不可逆膨胀。基于实验结果，还使用相对简单的模型来描述SEI的初始形成和稳定过程，并描述SEI厚度与预期SEI降解机制之间的关系。
