Chemical and Morphological Changes of Li鈥揙2 Battery Electrodes upon Cycling

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• 作者：Betar M. Gallant ; Robert R. Mitchell ; David G. Kwabi ; Jigang Zhou ; Lucia Zuin ; Carl V. Thompson ; Yang Shao-Horn
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：October 4, 2012
• 年：2012
• 卷：116
• 期：39
• 页码：20800-20805
• 全文大小：474K
• 年卷期：v.116,no.39(October 4, 2012)
• ISSN：1932-7455

文摘

We report considerable chemical and morphological changes of reaction products in binder-free, vertically aligned carbon nanotube (VACNT) electrodes during Li鈥揙₂ battery cycling with a 1,2-dimethoxyethane (DME)-based electrolyte. X-ray absorption near edge structure (XANES) of discharged oxygen electrodes shows direct evidence for the formation of Li₂CO₃-like species at the interface between VACNTs and Li₂O₂ but not significantly on the Li₂O₂ surfaces exposed to the electrolyte. Although Li₂O₂ and Li₂CO₃-like species were largely removed upon first charge, the oxidation kinetics became increasingly difficult during Li鈥揙₂ cycling, which is accompanied by the accumulation of Li₂CO₃ in the discharged and charged electrodes as evidenced by selected area electron diffraction (SAED) and transmission electron microscopy (TEM). Together, these results indicate that the irreversibility during Li鈥揙₂ cycling in DME can be attributed largely to the growth of Li₂CO₃-like species associated with the reactivity between carbon and Li₂O₂ or other reaction intermediates.