In Situ Transmission Electron Microscopy Observation of the Lithiation鈥揇elithiation Conversion Behavior of CuO/Graphene Anode

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• 作者：Qingmei Su ; Libing Yao ; Jun Zhang ; Gaohui Du ; Bingshe Xu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：October 21, 2015
• 年：2015
• 卷：7
• 期：41
• 页码：23062-23068
• 全文大小：550K
• ISSN：1944-8252

文摘

The electrochemical conversion behavior of metal oxides as well as its influence on the lithium-storage performance remains unclear. In this paper, we studied the dynamic electrochemical conversion process of CuO/graphene as anode by in situ transmission electron microscopy. The microscopic conversion behavior of the electrode was further correlated with its macroscopic lithium-storage properties. During the first lithiation, the porous CuO nanoparticles transformed to numerous Cu nanograins (2鈥? nm) embedded in Li₂O matrix. The porous spaces were found to be favorable for accommodating the volume expansion during lithium insertion. Two types of irreversible processes were revealed during the lithiation鈥揹elithiation cycles. First, the nature of the charge鈥揹ischarge process of CuO anode is a reversible phase conversion between Cu₂O and Cu nanograins. The delithiation reaction cannot recover the electrode to its pristine structure (CuO), which is responsible for about 鈭?5% of the capacity fading in the first cycle. Second, there is a severe nanograin aggregation during the initial conversion cycles, which leads to low Coulombic efficiency. This finding could also account for the electrochemical behaviors of other transition metal oxide anodes that operate with similar electrochemical conversion mechanism.