New Insights into Electrochemical Lithiation/Delithiation Mechanism of α-MoO3 Nanobelt by in Situ Transmission Electron Microscopy

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• 作者：Weiwei Xia ; Qiubo Zhang ; Feng Xu ; Litao Sun
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：8
• 期：14
• 页码：9170-9177
• 全文大小：612K
• 年卷期：0
• ISSN：1944-8252

文摘

The α-MoO<sub>3sub> nanobelt has great potential for application as anode of lithium ion batteries (LIBs) because of its high capacity and unique one-dimensional layer structure. However, its fundmental electrochemical failure mechanism during first lithiation/delithiation process is still unclear. Here, we constructed an electrochemical setup within α-MoO<sub>3sub> nanobelt anode inside a transmission electron microscope to observe in situ the mircostructure evolution during cycles. Upon first lithiation, the α-MoO<sub>3sub> nanobelt converted into numerous Mo nanograins within the Li<sub>2sub>O matrix, with an obvious size expansion. Interestingly, α-MoO<sub>3sub> nanobelt was found to undergo a two-stage delithiation process. Mo nanograins were first transformed into crystalline Li<sub>1.66sub>Mo<sub>0.66sub>O<sub>2sub> along with the disappearance of Li<sub>2sub>O and size shrink, followed by the conversion to amorphous Li<sub>2sub>MoO<sub>3sub>. This irreversible phase conversion should be responsible for the large capacity loss in first cycle. In addition, a fully reversile phase conversion between crystalline Mo and amorphous Li<sub>2sub>MoO<sub>3sub> was revealed accompanying the formation and disapperance of the Li<sub>2sub>O layer during the subsequent cycles. Our experiments provide direct evidence to deeply understand the distinctive electrochemical lithiation/delithiation behaviors of α-MoO<sub>3sub> nanobelt, shedding light onto the development of α-MoO<sub>3sub> anode for LIBs.