An Alternative Technique for Compounding and Fabrication of Lithium Ion Conductive PVB Films with Enhanced Thermal Properties and Electrochromic Performance

This research concerns the development of lithium ions conductive electrolyte from poly(vinyl butyral) (PVB) resin for use as a special interlayer film in electrochromic glass. To obtain the final PVB film with high ionic conductivity and thermal stability, a masterbatch was firstly prepared by mixing of PVB resin with lithium salt (LiClO4) and additives in an aqueous ethanol solution. After this, the dried masterbatch were converted into final films by an extrusion process. In this study, PVB film with the highest ionic conductivity value of 4.85×10−6 was obtained when the masterbatch was diluted with the neat PVB resin at the weight ratio of 2:1 in the extruder prior to fabrication. The results from cyclic voltammetry over 100 cycles, showed that performance of the electrochromic device (ITO/WO3/PVB electrolyte/ITO) fabricated by using the above PVB film is stable and reversible. In overall, this work demonstrates that ion conductive PVB films with compromised ionic conductivity and thermal stability can be prepared via an extrusion process without the need to modify chemical structure of PVB. This was carried out through the masterbatch approach, by introducing LiClO4 salts into the plasticized PVB via a solution mixing process prior to converting it into a final film via the extrusion process.