Endo Raimu, Ohnishi Tsuyoshi, Takada Kazunori, Masuda Takuya
Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
Research Center for Advanced Measurement and Characterization, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan.
J Phys Chem Lett. 2022 Aug 11;13(31):7363-7370. doi: 10.1021/acs.jpclett.2c01312. Epub 2022 Aug 4.
The electrochemical lithiation/delithiation in amorphous Si thin film electrodes deposited on a LLaZrTaO are dynamically analyzed by X-ray photoelectron spectroscopy. In the initial lithiation, the Si 2p peak corresponding to bulk Si significantly shifts to a lower binding energy due to the formation of LiSi and then monotonically with increasing capacity, i.e., the Li content in LiSi. When the lithiation stops at capacity of 2200 mAh g ( = ∼2.3), the peak recovers monotonically to a higher binding energy throughout the successive delithiation. When Li is inserted into LiSi up to 3400 mAh g ( = 3.5), however, the peak drastically shifts in the capacity range of 1520-1920 mAh g ( = 1.6-2.0) in the successive delithiation. This shift is attributed to the phase transition of crystalline LiSi formed in the preceding lithiation to the amorphous phase. The mechanism of initial lithiation/delithiation at each step is summarized on the basis of the state of charge, Li content in LiSi, and positions of XPS peaks.
通过X射线光电子能谱对沉积在LLaZrTaO上的非晶硅薄膜电极中的电化学锂化/脱锂过程进行了动态分析。在初始锂化过程中，对应于块状硅的Si 2p峰由于LiSi的形成而显著向较低结合能移动，然后随着容量增加（即LiSi中的锂含量）而单调变化。当锂化在2200 mAh g（= ∼2.3）的容量下停止时，在整个连续脱锂过程中，该峰单调恢复到较高结合能。然而，当锂插入LiSi至3400 mAh g（= 3.5）时，在连续脱锂过程中，该峰在1520 - 1920 mAh g（= 1.6 - 2.0）的容量范围内急剧移动。这种移动归因于先前锂化过程中形成的结晶LiSi向非晶相的相变。基于充电状态、LiSi中的锂含量以及XPS峰的位置，总结了每个步骤的初始锂化/脱锂机制。
