title: Size-Controlled Intercalation-to-Conversion Transition in Lithiation of Transition-Metal Chalcogenides-NbSe3.
abstract: 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.
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Langli
authors.initials: L
authors.lastname: Luo
authors.affiliation: Department of Materials Science & Engineering, Chinese Academy of Sciences Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China.
authors.forename: Benliang
authors.initials: B
authors.lastname: Zhao
authors.affiliation: Department of Materials Science & Engineering, Chinese Academy of Sciences Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xiang
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Chong-Min
authors.initials: CM
authors.lastname: Wang
keywords: Li ion batteries; NbSe3; conversion; in situ TEM; intercalation; transition-metal chalcogenides (TMCs)