X射线光电子能谱
阳极
电解质
相间
离子
石墨
分析化学(期刊)
化学状态
电池(电)
度量(数据仓库)
氧化态
化学
材料科学
电极
热力学
物理化学
物理
金属
复合材料
核磁共振
计算机科学
色谱法
有机化学
生物
遗传学
功率(物理)
数据库
作者
Kyunil Rah,Byung-Hee Choi,Chang Oh Kim
出处
期刊:Langmuir
[American Chemical Society]
日期:2024-03-28
卷期号:40 (14): 7550-7559
标识
DOI:10.1021/acs.langmuir.4c00113
摘要
Upon forming, the intensity or thickness of the solid electrolyte interphase (SEI) in a Li-ion battery (LIB) evolves to various states depending on the cell materials and operation conditions. Despite a crucial role in comprehending the behaviors of an LIB, its quantitative measure is far from satisfactory mainly because of the undue complexity of the concentration profiles of the comprising chemical species. Here, we calculate the depth profiles of atomic mole fractions of C and F and their ratio as RC/F = C/F of graphite anodes for LIBs in comparison to an X-ray photoelectron spectroscopy (XPS) experiment. To this end, we take a differential equation approach to dC/dt*, where t* is the reduced XPS etching time for depth. As a result, the respective analytical expression derived for C, F, and RC/F(t*) is verified to accurately account for the experiment. Moreover, we show that RC/F(t*) in the j state can be practically expressed in Rj(t*)≃αj(t*)1/γ+βj, where γ is a constant for a given anode. Based on this, we suggest ξj* = (αi + βi - βj)/αj as a measure of the SEI thickness evolution from the i to j state in terms of the cycle number. As an intriguing finding, the SEI thickness evolves up to about 3 times that of its initial state, beyond which it does not appear to grow any more.
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