期刊
ELECTROCHIMICA ACTA
卷 53, 期 22, 页码 6366-6371出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2008.04.057
关键词
alpha-LiFeO2; lithium ion batteries positive electrode; X-ray photoelectron spectroscopy; Mossbauer spectroscopy; differential scanning calorimetry; electrochemical impedance spectroscopy
in recent work U. Morales, J. Santos-Pefia, Electrochem. Commun. 9 (2007) 21161, we prepared nanosized a-LiFe02 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, a-LiFe02 was tested as a positive electrode material in a lithium battery under different regimes. Stabilised capacities up to 150 mAh g-1 were obtained under a C/4 regime. This lithium ferrite is therefore an attractive alternative to LiCoO2. (c) 2008 Elsevier Ltd. All rights reserved.
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