Polymer-free gel electrolyte and its application in TiO2 -based electrochromic devices

Abstract

Abstract Electrochromic devices based on polymer-free gel electrolytes (PFGE), offer several advantages over polymer electrolytes. The preparation and characterization of a fumed silica-based PFGE and its applications in TiO2 electrochromic devices (ECD) were the main aims of the present study. A series of liquid electrolytes were prepared by mixing lithium chloride (LiCl) and ethylene Glycol (EG). The total oxygen moles of EG to lithium ions of LiCl ratio (O: Li+) was altered from 5:1 to 80:1 and the ionic conductivities were measured. The highest ionic conductivity was observed for 15: 1 molar ratio with the value being the 1.28 × 10-2 S cm−1. In order to prepare PFGE, (10 wt. %) of fumed silica from the total weight of EG and LiCl were added to the optimized liquid electrolyte EG/LiCl as the polymer-free gelling agent. The maximum ionic conductivity was found in O: Li = 10: 1, with the value being 8.94 × 10-3 S cm-1. Notable electrochromic properties of TiO2/FTO were observed with higher optical modulation of 73% at 700 nm and a noticeable switching speed of Tbleaching= 42.5 s and Tcoloring= 16.7 s were observed.