Tuning the Morphology and Crystal Structure of Li2O2: A Graphene Model Electrode Study for Li–O2 Battery

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• 作者：Yao Yang ; Tao Zhang ; Xiaochen Wang ; Linfeng Chen ; Nian Wu ; Wei Liu ; Hanlin Lu ; Li Xiao ; Lei Fu ; Lin Zhuang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：August 24, 2016
• 年：2016
• 卷：8
• 期：33
• 页码：21350-21357
• 全文大小：466K
• 年卷期：0
• ISSN：1944-8252

文摘

The performance and the cyclability of the Li–O₂ batteries are strongly affected by the morphology and crystal structure of Li₂O₂ produced during discharge. In order to explore the details of growth and electrochemical decomposition of Li₂O₂, and its relationship with the cell performance, graphene films were used as model carbon electrodes and compared with electrodeposited Pd nanoparticles (NPs) on graphene. Multiple methods, including transmission/scanning electron microscopy (TEM/SEM), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and coin cell charge/discharge test, were employed for material characterization and reaction monitoring. The results showed that the presence of Pd NPs significantly changed the growth, morphology, and crystal structure of Li₂O₂ and reduced the charge overpotential by 1060 mV. All of these changes are ascribed to the stronger binding energy between LiO₂ and the Pd surface, resulting in the generation of amorphous Li₂O₂ with higher ionic conductivity of Li⁺ and O₂^2–, which in turn improve the cell charging performance.