Electronic structure evolution upon lithiation: A Li K-edge study of silicon oxide anode through X-ray Raman spectroscopy

• Published in: Journal of Power Sources Advances Vol. 29; p. 100155
• Main Authors: Huang, Hong-Jyun, Hsu, Chia-Shuo, Huang, Jin-Ya, Haw, Shu-Chih, Chen, Han-Yi, Hiraoka, Nozomu, Liao, Yen-Fa, Hu, Chih-Wei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024; Elsevier
• Subjects: Li K-edge; Lithium silicate; Lithium silicide; Silicon oxide; X-ray Raman spectroscopy; Lithium silicate; Silicon oxide; Lithium silicide; Li K-edge; X-ray Raman spectroscopy
• ISSN: 2666-2485; 2666-2485
• DOI: 10.1016/j.powera.2024.100155

The comprehensive understanding of the local structural changes surrounding lithium in lithium silicate (LixSiOy) and silicide (LixSi) within Li/SiOx batteries during the reversible structural transformations has been hindered by the limitations of current methodologies. In this work, the evolution of electronic structure at various lithiation stages has been addressed well by examining the Li K-edge spectra through X-ray Raman spectroscopy (XRS). The features observed in the Li K-edge XRS spectra provide insights into the development and alteration of LixSiOy, which emerges in the initial phases and may be accompanied by a reduction in the ionicity of Li–O bonding during lithiation. These features also agree well with the accompanying FDMNES code simulation. The correlation between electrochemical mechanisms and spectral characteristics is further explored by applying pseudo-Voigt peaks and cumulative pseudo-Voigt functions for fitting purposes. The absence of a significant edge shift indicates a similarity in the electronic structure of LixSi throughout lithiation, and no evidence of Li2O formation has also been observed. The Li K-edge XRS spectra exhibit strong agreement with the electrochemical behavior, establishing it as a valuable tool for investigating the evolution of electronic structure in Li/SiOx batteries. •X-ray Raman spectroscopy reveals the evolution of LixSiOy and LixSi.•Li K-edge XRS spectra reflect phase ratio and Li–O bonding ionicity variation.•Minute edge shift suggests the similarity of LixSi formed during lithiation.•Li K-edge XRS spectra support the absence of Li2O formation during lithiation.