In Situ Raman Observation of Dynamically Structural Transformation Induced by Electrochemical Lithium Intercalation and Deintercalation from Multi-Electrochromic V2O5 Thin Films

Understanding the dynamic nature of electrochemical interface induced by ion transfer is of great significance. Herein, in situ Raman spectroscopy combined with electrochemistry has been developed to real-time monitor the transfer of lithium ions at electrode-electrolyte interface and reveal the associated structure and performance variation of the vanadium pentoxide (V2O5) thin films on the indium tin oxide/silver/aluminum zinc oxide/poly(ethylene terephthalate) (ITO/Ag/AZO/PET) substrates. It is demonstrated that the Raman active/silent states of the vibrational modes of V-O, V-3-O, and V-O bonds, as well as the transformation of the V2O5 thin films from V2O5 to lithium vanadate (LixV2O5), can be reversibly changed with reversible extraction/insertion of lithium ions. In situ UV-vis spectroscopy in combination with in situ Raman analysis is applied to show that the reversible evolutions involving V2O5/LixV2O5 and VO bonding characteristic contribute to the multi-color electrochromic characteristic of the V2O5 thin films enabling a superior optical modulation of up to 75.41%. This experimental approach establishes a significative guideline for the more elaborate research on the dynamic nature of electrochemical interface.