TiO2-driven enhancement of electrochromic performance of polymer electrolytes: insights and mechanisms

Abstract

In recent years, electrochromic laminated glass has been widely used in automobiles and buildings due to its comfort and energy efficiency; however, its promotion is limited due to its complex structure. Herein, a TiO₂ enhanced conductive polyvinyl butyral (PVB) film has been constructed by a blending process. Its ionic conductivity can reach as high as 9.6 × 10⁻⁴ S cm⁻¹, which is attributed to the higher number of lithium ion transport channels in the composite film. Also, a corresponding electrochromic device (ECD) with a FTO/WO₃/PVB/NiO/FTO structure and dimensions of 10 × 10 cm² was assembled via a hot press process, and the enhancement in electrochromic performance was systematically evaluated. The tensile strength reached 34.6 MPa, the elongation at break reached 141%, and the adhesive strength was 5.5 MPa, which is equivalent to an automotive grade PVB film. Drop ball tests show that, for a 190 cm drop height with a 30 g mass, the device loses only 1.2% of its mass, which confirms its excellent safety. The device not only exhibited a fast response time of 4 s at a low voltage of ±3 V, but also demonstrated excellent electrochemical stability and cycling reversibility over 10 000 CV cycles. This work clarifies the coupling relationship between ion transport and device color change, demonstrating the potential application value in ECDs. Subsequent research can further integrate interfacial engineering strategies to advance the integration and application of CPE in practical devices.