Spectroelectrochemical study of the lithium insertion in vanadium(V) oxide xerogels

Author(s)

Huila, Manuel F. G. ^[1] ; Toma, Henrique E. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, BR-05508000 Sao Paulo - Brazil

• Document type: Journal article
• Source: Electrochimica Acta; v. 278, p. 236-244, JUL 10 2018.
• Web of Science Citations: 1

Abstract

Vanadium-oxide gels and xerogels are currently explored as versatile materials in lithium ion batteries. They consist of V2O5 nanoribbons composed by doubly-layered slabs joint by a strongly bond H3O+/H2O intercalated layer. Their thin films exhibit a complex electrochemical behavior encompassing four reduction waves at 0.38, 0.22, -0.42 and -0.81 V vs Ag/AgNO3 (0.503 vs SHE). In order to improve the understanding of such processes, a detailed spectroelectrochemical investigation was carried out based on visible-UV and confocal Raman spectroscopy. Accordingly, the first two waves were ascribed to the partial reduction of non-equivalent, localized V-V=O centers, keeping most of the representative vanadium-oxide vibrational features. At -0.4 V, a transition to a delocalized mixed-valence configuration became apparent in the optical and Raman spectra, leading to a dramatic current increase coupled with the insertion of lithium ions into the lamellar structure. At -0.8 V a complete conversion into the vanadium (IV) oxide form was observed from the spectroelectrochemical profiles. The nanoribbons doublylayered structure seems to be preserved, sustaining a reversible and reproducible electrochemical behavior along several repetitive voltammetric cycles. (C) 2018 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/24725-4 - Supramolecular chemistry and nanotechnology
• Grantee: Henrique Eisi Toma
• Support type: Research Projects - Thematic Grants