In situ TEM investigation of hexagonal WO3 irreversible transformation to Li2WO4. (October 2021)

• Record Type: Journal Article
• Authors: Wang, Zhenhua; Chen, Guoxin; Zhang, Hongliang; Liang, Lingyan; Gao, Junhua; Cao, Hongtao
• Is Part Of: Scripta materialia. Number 203(2021)
• Publication Date: 2021-10
• Subjects: Tungsten oxide -- Irreversible transformation -- Lithium tungstate -- In situ transmission electron microscopy; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2021.114090
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Lithium-ion migration at the WO3 /electrolyte interface is governed by the phase transformation mechanism by which metastable states are replaced from one phase to another. Herein, an in situ single nanowire-based cell is constructed to investigate the dynamic phase transformation and morphology evolution of h-WO3 nanowire in real-time during its deep lithiation. One of the most significant features of h-WO3 lithiation is the irreversible transformation from h-WO3 to Li2 WO4 . There are a large number of deep ion-trapping sites composed of 4 O atoms in Li2 WO4 crystal structure, that is, inserted lithium ions are irreversibly bound in these traps and nearly cannot be deintercalated. A mechanism on irreversible WO3 -to-Li2 WO4 transformation in deep lithiation reaction is demonstrated. With the aid of in situ transmission electron microscopy, we controllably triggered lithium-ion migration at the WO3 /electrolyte interface and directly visualized the nanoscale lithium-ion migration as a stop motion movie. Graphical abstract: Hexagonal WO3 irreversible transformation to Li2 WO4 can be experimentally demonstrated via in situ HRTEM in the deep lithiation process including the initial activation of the lithium metal, the wetting of a single WO3 nanowire and the migration of lithium ions into WO3, and the restructuring of hexagonal WO3 . Image, graphical abstract