Insights into the electrochemical activity of nanosized α-LiFeO<sub>2sub>

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• 作者：J. Morales ; J. Santos-Pe&#xf1 ; a ; R. Tr&#xf3 ; coli ; S. Franger ; E. Rodrí ; guez-Castell&#xf3 ; n
• 关键词：src="http ; //www.sciencedirect.com/scidirimg/entities/204e.gif" alt="greek small letter alpha" title="greek small letter alpha" border="0">-LiFeO<sub>2sub> ; Lithium ion batteries positive electrode ; X-ray photoelectron spectroscopy ; M&#xf6 ; ssbauer s
• 刊名：Electrochimica Acta
• 出版年：2008
• 期刊代码：30_00134686
• 类别：ch
• 出版时间：20 September 2008
• 卷：53
• 期：22
• 页码：6366-6371
• 文件大小：570 K

摘要

In recent work [J. Morales, J. Santos-Pe&#xf1;a, Electrochem. Commun. 9 (2007) 2116], we prepared nanosized src="http://www.sciencedirect.com/scidirimg/entities/204e.gif" alt="greek small letter alpha" title="greek small letter alpha" border="0">-LiFeO<sub>2sub> with increased electrochemical activity in lithium cells relative to various lithium ferrite polymorphs. In this work, we studied the previous electrodes in different charge states in order to obtain a more accurate picture of the phenomena occurring during cycling. Ex situ X-ray photoelectron spectroscopy (XPS) measurements confirmed the oxidation/reduction of iron atoms during the charge/discharge process. The electrochemical impedance spectroscopy results suggested that the electrolyte is not oxidised during the first charge, but rather than a solid electrolyte interface is formed after one cycle. Also, thermal tests revealed that Fe(IV) present in the electrodes reacted with the electrolyte to form oxidised carbon species. Finally, src="http://www.sciencedirect.com/scidirimg/entities/204e.gif" alt="greek small letter alpha" title="greek small letter alpha" border="0">-LiFeO<sub>2sub> was tested as a positive electrode material in a lithium battery under different regimes. Stabilised capacities up to 150 mAh g<sup>−1sup> were obtained under a C/4 regime. This lithium ferrite is therefore an attractive alternative to LiCoO<sub>2sub>.