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. 2020 Aug 20;11(16):6649-6654. doi: 10.1021/acs.jpclett.0c01906. Epub 2020 Aug 5.
X-ray photoelectron spectroscopy is applied to electrochemical lithiation/delithiation processes of an amorphous Si electrode sputter-deposited on a LiLaZrTaO solid electrolyte. After the first lithiation, a broad Li peak appears at the Si surface, and peaks corresponding to bulk Si and Si suboxide significantly shift to lower binding energy. The appearance of the Li peak and shift of the Si peaks confirm the formation of lithium-silicide and lithium-silicates due to the lithiation of Si and native suboxide. The composition of lithium-silicide is estimated to be LiSi by quantitative analysis of electrochemical response and photoelectron spectra. Peak fitting analysis shows the formation of LiO and LiCO due to side reactions. Upon the following delithiation, the peak corresponding to LiSi phase shifts back to higher binding energy to form LiSi phase, while lithium-silicates, LiO, and LiCO remained as irreversible species. Thus, electrochemical reactions accompanied with lithiation/delithiation processes are successfully observed.
X射线光电子能谱被应用于溅射沉积在LiLaZrTaO固体电解质上的非晶硅电极的电化学锂化/脱锂过程。首次锂化后，Si表面出现一个宽的Li峰，对应体相Si和亚氧化硅的峰显著向较低结合能移动。Li峰的出现和Si峰的移动证实了由于Si和原生亚氧化物的锂化而形成了硅化锂和硅酸锂。通过电化学响应和光电子能谱的定量分析，硅化锂的组成估计为LiSi。峰拟合分析表明由于副反应形成了LiO和LiCO。在随后的脱锂过程中，对应LiSi相的峰移回到较高结合能以形成LiSi相，而硅酸锂、LiO和LiCO则作为不可逆物种保留下来。因此，成功观察到了伴随锂化/脱锂过程的电化学反应。
