Rapid response and wide-band regulation of an electrochromic device achieved by ultra-small V2O5 nanodots and a Zn2+/Li+ electrolyte

Abstract

The distinctive multicolor characteristics of vanadium oxide (V₂O₅) set it apart from other inorganic electrochromic materials. Nevertheless, its practical applications are considerably constrained by several factors, including solubility in aqueous electrolytes, inferior conductivity, and especially limited light modulation. In this study, we introduce an innovative approach for the preparation of ultra-small V₂O₅ nanodots, which are expected to offer an increased number of active sites, thereby improving the efficiency of redox reactions. A comparative analysis of the performance of the V₂O₅ electrode in different cation electrolytes shows that Li⁺ serves as the most suitable match due to its small ionic radius and monovalent nature. As a result, the V₂O₅ electrochromic electrode demonstrates exceptional electrochromic performance, characterized by its ability to undergo wide-band adjustments attributable to the polarization reactions associated with cation insertion. As a proof of concept, we utilized V₂O₅ nanodots and a Zn²⁺/Li⁺ electrolyte to develop a multicolor transparent electrochromic display using zinc as the anode. Given the enhanced performance of the Zn²⁺/Li⁺ electrolyte and the V₂O₅ nanodot cathode, the prototype of the electrochromic display exhibits impressive performance, such as optical contrasts of 61.2% (728 nm) and 50.2% (1200 nm), a bleaching time of 8.5 s, a coloring time of 10.4 s, and an energy recovery efficiency of 31.65%. This work provides a significant material foundation for advancing vanadate-based electrochromic display technology and offers valuable insights into the selection of electrolytes for vanadate devices.