In Situ Study of Lithiation and Delithiation of MoS2 Nanosheets Using Electrochemical Liquid Cell Transmission Electron Microscopy

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• 作者：Zhiyuan Zeng ; Xiaowei Zhang ; Karen Bustillo ; Kaiyang Niu ; Christoph Gammer ; Jun Xu ; Haimei Zheng
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：August 12, 2015
• 年：2015
• 卷：15
• 期：8
• 页码：5214-5220
• 全文大小：573K
• ISSN：1530-6992

文摘

We report the observation of lithiation/delithiation of MoS₂ nanosheets in a LiPF₆/EC/DEC commercial electrolyte for the application of lithium-ion batteries using electrochemical liquid cell transmission electron microscopy (TEM). Upon discharge in a voltage range of 1.8鈥?.2 V, MoS₂ on the Ti electrode underwent irreversible decomposition resulting in fragmentation of the MoS₂ nanosheets into 5鈥?0 nm MoS₂ nanoparticles. Repeated experiments also show that some MoS₂ nanosheets do not decompose upon lithiation. Instead, lithiation induced structural expansion and deformation has been observed. A solid鈥揺lectrolyte interface (SEI) was formed on the anode side of the Ti electrode in contact with Li metal. The SEI layer is composed of LiF nanocrystals distributed within the entire layer with the constituent elements C, O, and F. However, no passivation film was observed on the cathode side of the Ti electrode with MoS₂ nanosheets on it. Such an in situ electrochemical liquid cell TEM study sheds light on battery degradation mechanisms.