Gao Aosong, Lai Hao, Duan Mingqiu, Chen Si, Huang Wenyu, Yang Muzi, Gong Li, Chen Jian, Xie Fangyan, Meng Hui
School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510006, P. R. China.
Instrumental Analysis & Research Center, Sun Yat-sen University, Guangzhou 510275, P. R. China.
ACS Appl Mater Interfaces. 2025 Feb 5;17(5):8513-8525. doi: 10.1021/acsami.4c17553. Epub 2025 Jan 27.
The solid electrolyte interphase (SEI) is considered to be the key to the performance of lithium metal batteries (LMBs). The analysis of the SEI and cathode electrolyte interphase (CEI) composition (especially F 1s spectra) by X-ray photoelectron spectroscopy (XPS) has become a consensus among researchers. However, the surface-sensitive XPS characterization is susceptible to LiF artifacts due to several factors, leading to the overexaggerated role of LiF in the analysis of the SEI and CEI. In this paper, we conduct a systematic study on the reasons for the LiF artifacts in the XPS characterization of LMBs. The decomposition of the SEI and CEI components under argon ion sputtering, the reaction between LiCO and LiPF in the electrolyte, influence of different sample pretreatments, the selection of the XPS measurement region, and the measurement time on the resulting spectra are investigated. The results indicate that the high content of LiF in the SEI and CEI may be attributed to the LiF artifacts, and the role of LiF in the SEI may be overexaggerated as a consequence. This work sounds an alarm about the potential misuse of argon ion sputtering and the lack of rigorous XPS characterization in SEI studies. This work also helps to set up standardized XPS characterization to provide a more accurate understanding of the role of SEI components.
固体电解质界面（SEI）被认为是锂金属电池（LMBs）性能的关键。通过X射线光电子能谱（XPS）分析SEI和阴极电解质界面（CEI）的组成（特别是F 1s光谱）已成为研究人员的共识。然而，由于多种因素，表面敏感的XPS表征容易受到LiF假象的影响，导致在SEI和CEI分析中LiF的作用被过度夸大。在本文中，我们对LMBs的XPS表征中LiF假象产生的原因进行了系统研究。研究了氩离子溅射下SEI和CEI成分的分解、电解质中LiCO与LiPF之间的反应、不同样品预处理的影响、XPS测量区域的选择以及测量时间对所得光谱的影响。结果表明，SEI和CEI中LiF的高含量可能归因于LiF假象，结果LiF在SEI中的作用可能被过度夸大。这项工作对氩离子溅射的潜在误用以及SEI研究中缺乏严格的XPS表征敲响了警钟。这项工作也有助于建立标准化的XPS表征，以便更准确地理解SEI成分的作用。
