Zhou Mengyuan, Feng Chen, Xiong Ruoyu, Li Longhui, Huang Tianlun, Li Maoyuan, Zhang Yun, Zhou Huamin
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
China Development Bank Corporation Hubei Branch, Wuhan 430074, China.
ACS Appl Mater Interfaces. 2022 Jun 1;14(21):24875-24885. doi: 10.1021/acsami.2c02584. Epub 2022 May 2.
Solid electrolyte interphase (SEI) is regarded as the key to developing stable and long-cycling lithium metal batteries (LMBs). The inevitable stress caused by the Li-metal anode expansion/contraction and the battery encapsulation is crucial to the SEI growth and properties. Herein, we perform reactive force field (ReaxFF) molecular dynamics simulations to investigate the structure and property variation of the pressure-induced SEI. The pressure boosts the SEI structure delamination and reduces the porosity based on the quantitative analysis of the charge spectrum and porous structure, which contributes to the formation of a thin and dense SEI. Meanwhile, the phase diagram combined with the pressure and salt concentration effects is established to obtain the proper trade-off between SEI mechanical and transport properties, demonstrating that the Li diffusion coefficients of the pressure-induced SEI can be improved by the high salt concentration when Young's modulus increases at the same time. The findings not only provide molecular insights into the SEI structure variation but also offer guidance and directions for optimizing the pressure-induced SEI property toward high-performance LMBs.
固体电解质界面（SEI）被视为开发稳定且长循环锂金属电池（LMB）的关键。锂金属阳极膨胀/收缩以及电池封装所产生的不可避免的应力对于SEI的生长和性能至关重要。在此，我们进行反应力场（ReaxFF）分子动力学模拟，以研究压力诱导的SEI的结构和性能变化。基于电荷谱和多孔结构的定量分析，压力促进了SEI结构分层并降低了孔隙率，这有助于形成薄而致密的SEI。同时，建立了结合压力和盐浓度效应的相图，以在SEI的机械性能和传输性能之间取得适当的平衡，表明当杨氏模量同时增加时，高盐浓度可提高压力诱导的SEI的锂扩散系数。这些发现不仅为SEI结构变化提供了分子层面的见解，还为优化压力诱导的SEI性能以实现高性能LMB提供了指导和方向。
