Size-Controlled Intercalation-to-Conversion Transition in Lithiation of Transition-Metal Chalcogenides—NbSe3

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• 作者：Langli Luo ; Benliang Zhao ; Bin Xiang ; Chong-Min Wang
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：January 26, 2016
• 年：2016
• 卷：10
• 期：1
• 页码：1249-1255
• 全文大小：472K
• ISSN：1936-086X

文摘

Transition-metal chalcogenides (TMCs) can be used either as intercalation cathodes or as conversion-type anodes for lithium ion batteries, for which two distinctively different lithiation reaction mechanisms govern the electrochemical performance of TMCs. However, the factors that control the transition of lithiation mechanisms remain elusive. In this work, we investigated the lithiation process of NbSe₃ ribbons using in situ transmission electron microscopy and observed a size-dependent transition from intercalation to the conversion reaction. Large NbSe₃ ribbons can accommodate high concentrations of Li⁺ through intercalation by relaxing their internal spacing, while lithiation of small NbSe₃ ribbons proceeds readily to full conversion. We found that the size-dependent variation of the lithiation mechanism is associated with both Li⁺ diffusion in NbSe₃ and the accommodation of newly formed phases. For large NbSe₃ ribbons, the intercalation-to-conversion transition is impeded by both long-range Li⁺ diffusion and large-scale accommodation of volume expansion induced by the formation of new phases. These results demonstrate the inherent structural instability of NbSe₃ as an intercalation cathode and its high lithiation rate as a promising conversion-type anode.