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20210404 Li_K_XAS_ChemRxiv_withSI.pdf (2.35 MB)

Controlled Experiments and Optimized Theory of Absorption Spectra of Li Metal and Salts

submitted on 06.04.2021, 03:39 and posted on 07.04.2021, 09:42 by Subhayan Roychoudhury, Zengqing Zhuo, Ruimin Qiao, Liwen Wan, Yufeng Liang, Feng Pan, Yi-de Chuang, David Prendergast, Wanli Yang
Abstract: Investigations of Li metal and ionic compounds through experimental and theoretical spectroscopy has been of tremendous interest due to their prospective applications in Li-metal and Li-ion batteries. Li K-edge soft X-ray absorption spectroscopy (sXAS) provides the most direct spectroscopic characterization; unfortunately, due to the low core-level energy and the highly reactive surface, Li-K sXAS of Li metal has been extremely challenging, as evidenced by many controversial reports. Here, through controlled and ultra-high energy resolution experiments of two kinds of in-situ prepared samples, we report the intrinsic Li-K sXAS of Li-metal that displays a prominent leading peak, which has never been revealed before. Furthermore, theoretical simulations show that the Li-K sXAS is strongly affected by the response of the valence electrons to the core-hole due to the low number of valence electrons in Li. We successfully reproduce the Li-K sXAS by state-of-the-art calculations with considerations of a number of relevant parameters such as temperature, resolution, and especially contributions from transitions which are forbidden in the so-called single-particle treatment. Such a comparative experimental and theoretical investigation is further extended to a series of Li ionic compounds, which highlight the importance of considering the total and single-particle energies for obtaining an accurate alignment of the spectra. Our work provides the first reliable Li-K sXAS of Li metal surface with advanced theoretical calculations. The experimental and theoretical results provide a critical benchmark for studying Li surface chemistry in both metallic and ionic states.


Email Address of Submitting Author


Lawrence Berkeley National Lab


United States

ORCID For Submitting Author


Declaration of Conflict of Interest