Scanning X-ray Fluorescence Imaging Study of Lithium Insertion into Copper Based Oxysulfides for Li-Ion Batteries

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• 作者：Rosa Robert ; Dongli Zeng ; Antonio Lanzirotti ; Paul Adamson ; Simon J. Clarke ; Clare P. Grey
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：July 24, 2012
• 年：2012
• 卷：24
• 期：14
• 页码：2684-2691
• 全文大小：557K
• 年卷期：v.24,no.14(July 24, 2012)
• ISSN：1520-5002

文摘

Ex situ and in situ Synchrotron X-ray fluorescence imaging coupled with selective micro-X-ray absorption near-edge spectroscopy (渭XANES) and micro-X-ray diffraction (渭XRD) were used to investigate the electrochemical lithiation of the layered oxysulfide Sr₂MnO₂Cu_3.5S₃. Microfocused X-ray fluorescence (XRF) imaging was used to image the elemental components within the battery electrode while 渭XANES and 渭XRD provided information about the Cu oxidation state and phase distribution, respectively. Sr₂MnO₂Cu_3.5S₃ operates by a combined insertion/displacement mechanism. After 1 mol of Li intercalation, Cu metal extrusion is observed by 渭XRD, which also reveals the formation of the Sr₂MnO₂Cu_3.5鈥?i>xLi_xS₃ phase. Ex situ 渭XRF images of the electrode after 3.75 mol of Li intercalation show segregated Cu metal and Sr₂MnO₂Cu_3.5鈥?i>xLi_xS₃ particles, while in situ 渭XRF imaging experiments reveal that the Cu and Mn elemental distribution maps are highly correlated to the particle orientation giving different results when the particle is oriented either perpendicular or parallel to the incident beam. In situ electrochemical synchrotron XRF imaging has the advantage over the ex situ mode in that it allows the reaction mechanism of a single particle to be followed vs time. In situ 渭XRF imaging data suggest that the microstructure of the electrode, on a microscale level, is not affected by the Cu extrusion process.

Keywords:

scanning X-ray fluorescence imaging; Li-ion batteries; cathode materials; insertion/displacement reactions; oxysulfides