Chemical and Morphological Changes of Li-O2 Battery Electrodes upon Cycling
Chemical and Morphological Changes of Li-O2 Battery Electrodes upon Cycling
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DOI：
10.1021/jp308093b
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发表时间：
2012-10-04
影响因子：
3.7
通讯作者：
Shao-Horn, Yang
中科院分区：
文献类型：
--
作者：
Gallant, Betar M.;Mitchell, Robert R.;Shao-Horn, Yang
我们报告了在使用基于 1,2-二甲氧基乙烷 (DME) 的电解质的 Li-O-2 电池循环过程中，无粘合剂垂直排列碳纳米管 (VACNT) 电极中的反应产物发生了相当大的化学和形态变化。放电氧电极的近边缘结构 (XANES) 的 X 射线吸收显示了在 VACNT 和 Li2O2 之间的界面处形成类 Li2CO3 物质的直接证据，但在暴露于电解质的 Li2O2 表面上不明显。尽管 Li2O2 和 Li2CO3 类物质在第一次充电时大部分被去除，但在 Li-O-2 循环过程中，氧化动力学变得越来越困难，并且伴随着 Li2CO3 在放电和充电电极中的积累，如选区电子衍射 (SAED) 和透射电子显微镜 (TEM) 所证明的那样。总之，这些结果表明，DME 中 Li-O-2 循环过程中的不可逆性很大程度上归因于与碳和 Li2O2 或其他反应中间体之间的反应性相关的类 Li2CO3 物质的生长。
We report considerable chemical and morphological changes of reaction products in binder-free, vertically aligned carbon nanotube (VACNT) electrodes during Li-O-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-O-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-O-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.