Interfacial Effects on Lithium Superoxide Disproportionation in Li-O2 Batteries

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• 作者：Dengyun Zhai ; Kah Chun Lau ; Hsien-Hau Wang ; Jianguo Wen ; Dean J. Miller ; Jun Lu ; Feiyu Kang ; Baohua Li ; Wenge Yang ; Jing Gao ; Ernesto Indacochea ; Larry A. Curtiss ; Khalil Amine
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：February 11, 2015
• 年：2015
• 卷：15
• 期：2
• 页码：1041-1046
• 全文大小：453K
• ISSN：1530-6992

文摘

During the cycling of Li-O₂ batteries the discharge process gives rise to dynamically evolving agglomerates composed of lithium鈥搊xygen nanostructures; however, little is known about their composition. In this paper, we present results for a Li-O₂ battery based on an activated carbon cathode that indicate interfacial effects can suppress disproportionation of a LiO₂ component in the discharge product. High-intensity X-ray diffraction and transmission electron microscopy measurements are first used to show that there is a LiO₂ component along with Li₂O₂ in the discharge product. The stability of the discharge product was then probed by investigating the dependence of the charge potential and Raman intensity of the superoxide peak with time. The results indicate that the LiO₂ component can be stable for possibly up to days when an electrolyte is left on the surface of the discharged cathode. Density functional calculations on amorphous LiO₂ reveal that the disproportionation process will be slower at an electrolyte/LiO₂ interface compared to a vacuum/LiO₂ interface. The combined experimental and theoretical results provide new insight into how interfacial effects can stabilize LiO₂ and suggest that these interfacial effects may play an important role in the charge and discharge chemistries of a Li鈥揙₂ battery.