Different oxygen redox participation for bulk and surface: A possible global explanation for the cycling mechanism of Lib>1.20b>Mnb>0.54b>Cob>0.13b>Nib>0.13b>Ob>2b>

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• 作者：Hideyuki Koga^a ; ^b ; Laurence Croguennec^a ; ^{crog@icmcb-bordeaux.cnrs.fr} ; Michel Mé ; né ; trier^a ; Philippe Mannessiez^a ; Franç ; ois Weill^a ; Claude Delmas^a
• 关键词：Layered oxide ; Lithium batteries ; X-ray diffraction ; Overcapacity ; Oxygen oxidation ; Oxygen loss
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：15 August, 2013
• 年：2013
• 卷：236
• 期：Complete
• 页码：250-258
• 全文大小：3244 K

文摘

Synthesis of Lib>1.20b>Mnb>0.54b>Cob>0.13b>Nib>0.13b>Ob>2b> at different temperatures allows modifying particle sizes and specific surface areas while keeping very similar structures for the materials from the local scale to long distances. X-ray diffraction analysis reveals that irreversible structural reorganization of this lithium and manganese-rich layered oxide occurs during the 1st charge and continues during a few cycles. A mixture of two phases is formed on the high voltage plateau and is then maintained, showing that the material obtained upon cycling is metastable and out of equilibrium. Depending on the particles' size and on the cycling conditions (Cycling rate, temperature and number of cycles) the nature of the materials formed changes, with especially a difference in distribution between the two phases observed. We propose that these phenomena are intimately linked to oxygen participation to the redox processes, for one phase with (reversible) oxygen oxidation only and for the second phase up to (irreversible) oxygen loss.