School of Engineering, Brown University , 182 Hope Street, Box D, Providence, Rhode Island 02912, United States.
General Motors Global R&D Center , 30500 Mound Road, Warren, Michigan 48090, United States.
ACS Appl Mater Interfaces. 2017 Aug 30;9(34):28406-28417. doi: 10.1021/acsami.7b06647. Epub 2017 Aug 18.
The chemical and mechanical stability of SEI layers are particularly important for high capacity anode materials such as silicon, which undergoes large volume changes (∼300%) during cycling. In this work, we present a novel approach for applying controlled strains to SEI films with patterned Si electrodes to systematically investigate the impact of large volume changes on SEI formation and evolution. Comparisons between patterned silicon islands and continuous silicon thin films make it possible to correlate the irreversible capacity losses due to expansion and contraction of underlying silicon. The current work demonstrates that strain in the SEI layer leads to more lithium consumption. The combination of in situ AFM and electrochemical lithium loss measurements provides further information on SEI layer growth. These experiments indicate that in-plane strains in the SEI layer lead to substantial increases in the amount of inorganic phase formation, without significantly affecting the overall SEI thickness. These observations are further supported with EIS and TOF-SIMS results. A map of irreversible capacity evolution with strain in the SEI is obtained from the experimental results.
SEI 层的化学和机械稳定性对于高容量阳极材料（如硅）尤为重要，因为硅在循环过程中会经历较大的体积变化（约 300%）。在这项工作中，我们提出了一种在具有图案化 Si 电极的 SEI 薄膜上施加受控应变的新方法，以系统地研究大体积变化对 SEI 形成和演变的影响。图案化硅岛与连续硅薄膜之间的比较使得可以关联由于底层硅的膨胀和收缩而导致的不可逆容量损失。目前的工作表明，SEI 层中的应变会导致更多的锂消耗。原位 AFM 和电化学锂损耗测量的结合提供了有关 SEI 层生长的进一步信息。这些实验表明，SEI 层中的面内应变会导致无机相形成量的大量增加，而不会显著影响整体 SEI 厚度。这些观察结果还得到了 EIS 和 TOF-SIMS 结果的支持。从实验结果中获得了 SEI 应变的不可逆容量演化图。
