An X-ray Absorption Spectroscopy Study of the Cathodic Discharge of Ag2VO2PO4: Geometric and Electronic Structure Characterization of Intermediate phases and Mechanist

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• 作者：Christopher J. Patridge ; Cherno Jaye ; Tesfaye A. Abtew ; Bruce Ravel ; Daniel A. Fischer ; Amy C. Marschilok ; Peihong Zhang ; Kenneth J. Takeuchi ; Esther S. Takeuchi ; Sarbajit Banerjee
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：July 28, 2011
• 年：2011
• 卷：115
• 期：29
• 页码：14437-14447
• 全文大小：1160K
• 年卷期：v.115,no.29(July 28, 2011)
• ISSN：1932-7455

文摘

Bimetallic phosphorus oxides have emerged as attractive candidates for use as cathode materials in the next generation of lithium-based batteries owing to the operation of multielectron transfer processes and thermochemical stabilities conferred by the incorporation of phosphate groups. In particular silver vanadium phosphorus oxide, Ag₂VO₂PO₄, shows a much desired in situ conductivity enhancement upon discharge resulting in inherently high power capability with minimal conductive additives needed. However, the amorphization of Ag₂VO₂PO₄ during electrochemical discharge precludes the use of standard diffraction tools to monitor changes in the local electronic and geometric structure. Here, we have utilized a combination of V K-, V L-, Ag K-, and O K-edge X-ray absorption fine structure spectroscopy to determine the local vanadium and silver oxidation states, local coordination geometry, and stoichiometry for Ag₂VO₂PO₄ samples with varying extents of electrochemical lithiation. Soft X-ray V L- and O K-edge measurements provide a detailed orbital-specific picture of changes in vanadium electronic structure upon discharge.