Inhibiting Vanadium Dissolution of Potassium Vanadate for Stable Transparent Electrochromic Displays

Vanadium oxides are highly valued as electrochromic materials because of their multicolor capabilities. However, their practical applications have been limited due to challenges such as the dissolution of vanadate into aqueous electrolytes, leading to poor long-term stability. Herein, a solution is proposed to the vanadate dissolution issue by utilizing a hybrid electrolyte consisting of tetraethylene glycol dimethyl ether (TEGDME) and water. This electrolyte has the unique ability to form a robust cathode electrolyte interface layer on vanadium oxide electrodes. As a proof of concept, zinc-anode-based multicolor transparent electrochromic displays are prepared using layered potassium vanadate (K₂V₆O₁₆·1.5H₂O, KVO) with a TEGDME-water hybrid electrolyte. By soaking the KVO electrode in the hybrid electrolyte, it is demonstrated that KVO has remarkable stability against dissolution. Furthermore, it is shown that KVO has superior electrochromic performance compared to sodium vanadate (NaV₃O₈·1.5H₂O, SVO), due to the wide KVO interlayer spacing. Given the enhanced performance of this hybrid electrolyte and KVO cathode material, a zinc-anode-based electrochromic display prototype is shown to exhibit compelling performance. As such, this work is expected to be a significant catalyst for accelerating the development of vanadate-based electrochromic displays.