Electrochemical Delithiation/Relithiation of LiCoPO4: A Two-Step Reaction Mechanism Investigated by in Situ X-ray Diffraction, in Situ X-ray Absorption Spectroscopy, and ex

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• 作者：Maximilian Kaus ; Ibrahim Issac ; Ralf Heinzmann ; Stephen Doyle ; Stefan Mangold ; Horst Hahn ; Venkata Sai Kiran Chakravadhanula ; Christian K眉bel ; Helmut Ehrenberg ; Sylvio Indris
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：August 7, 2014
• 年：2014
• 卷：118
• 期：31
• 页码：17279-17290
• 全文大小：919K
• ISSN：1932-7455

文摘

LiCoPO₄ was synthesized by a solid-state and a supercritical solvo-thermal method. In situ X-ray absorption near-edge structure (XANES) experiments were evaluated on the basis of full-cycle experiments confirming the predominantly reversible character of the redox reaction. In situ X-ray diffraction (XRD) measurements were performed to follow structural changes during cycling indicating the existence of an intermediate phase upon cycling. The local phosphorus and lithium environments were studied by ex situ ³¹P and ⁷Li NMR at different states of charge proving the existence of an intermediate phase of the composition Li_2/3CoPO₄. On the basis of these findings, a model of the (de)lithiation process of LiCoPO₄ is developed and discussed.